"You can bypass the Roland GI-20 GK-MIDI Interface usb/midi and use it's 5-pin
midi connector to plug into the new audio interface midi in."
 
  Are you sure that works for the Quad Capture? I've read in old posts (pre-Quad
Capture) that won't work:
  http://forum.cakewalk.com/Using-Roland-GK2a-or-GK3-m200845.aspx
 
  I'd like the least expensive good solution.

glenster
  "You can bypass the Roland GI-20 GK-MIDI Interface usb/midi and use it's 5-pin
midi connector to plug into the new audio interface midi in."
 
  Are you sure that works for the Quad Capture? I've read in old posts (pre-Quad
Capture) that won't work:
http://forum.cakewalk.com/Using-Roland-GK2a-or-GK3-m200845.aspx
 
  I'd like the least expensive good solution.

I'm not familiar with the interface, is the GI-20 GK-MIDI Interface only handles midi or is it a sound module also ?
 
If the purpose of the USB port for GI-20 GK-MIDI Interface is for MIDI data transmission (none audio), then it's standard 5-pin MIDI port should transmit the same information. 

  Roland GI-20 GK-MIDI Interface
  http://www.rolandus.com/products/details/563

I've downloaded the manual and here is my observation :
 
(ref : manual page 40, point 1 of MIDI Implementation)
You only need the USB if you're connecting a sound module/keyboard to the GI-20 (via 5-pin MIDI out) and with a connection to the computer at the same time (manual example page 10). This is for recorded midi data from the computer (such as Sonar), during playback to pass via USB to the GI-20, and in turn, pass to the sound module.
 
However, if you're using soft synth, there is no need to use external MIDI sound module.
 
Alternately, if you're using a sound module and in the event that the driver doesn't work with newer Windows, you can always get a multi-MIDI in/out device and route your sound module to this device (G1-20 to MIDI in #1, sound module to MIDI out #2).
 
Now, hopefully an actual user of the GI-20 can verify if this is indeed true; but I'm quite sure this is true :)

http://cms.rolandus.com/a...ery/gi-20_back_gal.jpg

The thing with Guitar synths is they have better latency when triggering their dedicated sound module, Things have most likely improved since I bought my GR 50 but if I use the MIDI outs to trigger a soft synth the latency is terrible. No problem as all you have to do is monitor the sound module while recording and then pull the midi track back a bit in time. 
 
Seeing as the unit you have can send MIDI over both MIDI and the USB you actually don't need MIDI ports on your interface, but for what it's worth they are still an asset if you are ever interested in driving outboard gear that is older and doesn't use USB. If you use USB then you need separate drivers for it.  I like good old MIDI ports for this reason, your interface drivers take care of both audio and MIDI. 
 
Make a list, like you just did, of all the ins and outs you would like and plan on possible future needs. Most important is you requirements for Round trip Latency performance. RTL
 
You defiantly will want the RME interface if your planning on using things like Guitar Rig. 
 Most USB interfaces perform well in all aspects but the RTL. PCIe cards and Firewire are still the top performers. Read this very informative thread. 
 
http://www.gearslutz.com/board/music-computers/618474-audio-interface-low-latency-performance-data-base-20.html
 
note; Roland's are not even on the list  or is my  Focusrite. I don't need RTL to be low because I use direct monitoring and stay away from situations that require better performance. Down the road I will look into buying one of the interfaces from the top of the list here. 
 If good RTL performance is not on your list of requirements then it's really just about connectivity and reliable drivers.  Here is my review for the Scarlett 6i6 to give you an idea of makeing a shopping list. 
 
http://www.gearslutz.com/board/reviews/906141-focusrite-scarlett-6i6.html
 
 
You don't mention if you have a version of Sonar at this point. One good thing about the Roland interface is it comes with Sonar X1 LE which will give you a cheap upgrade path to X3e so this has some value, otherwise the Scarlett line up beats Ronald in price point for features. 
 
 

  RTL info on the Roland Quad Capture and Steinberg UR44:
 
  the Quad-Capture considerably better than the Duo-Capture Ex, and in the same
ball-park as the RME.
  http://www.gearslutz.com/board/music-computers/899048-steinberg-ur22-vs-komplete-audio-6-vs-roland-quad-capture.html
 
  Steinberg UR44 review
  http://www.musictech.net/2014/04/steinberg-ur44-review/
 
  The Steinberg UR-44 is a new (relatively low cost) audio interface that offers
good fidelity and low round-trip latency.
  http://forum.cakewalk.com/What39s-a-really-good-Audio-Interface-wlowest-latency-m3010201.aspx
 
  Latency-Free Monitoring with FX UR44 offers zero-latency monitoring with FX
thanks to the included dspMixFx software with integration for Cubase owners with
auto-setup, custom views, and much more.
  http://www.bhphotovideo.com/c/product/1018651-REG/steinberg_ur44.html
 
  I have a Roland-ready Strat with a (correction--not GK-3) GK-2A divided pickup
and a GI-20, also Yamaha DD-55 drums and an Oxygen 8 keyboard. All this gear is
about 10? years old.  Please bear with me: I haven't recorded yet and I'm not
familiar with some of the terms being used.  I finally got a new PC and want to
get whatever interface I need and Cakewalk or Cubase for one man recording.  I'm
splurging but I'm actually on a low income and can't really use any $1,500
solutions.
  http://usa.yamaha.com/products/musical-instruments/drums/drums_digital_percussion/portable_digital_drums/dd_series/dd-55/?mode=model
  http://www.amazon.com/M-Audio-OXYGEN-25-Key-Controller-9900-41392-00/dp/B000ED4CUW
 

Zero latency / direct monitoring may help audio recording. But in the case of midi guitar, it will depend how fast the GI-20 output the MIDI data, in turn driving the external sound module, or for fast soft synth playback, a fast CPU helps. You can still do direct monitoring from the actual Strat guitar sound.

 
  Roland support:
  Connect the Roland-Ready Strat with a GK-2a pickup to the GI-20.  Connect the
GI-20 MIDI out to the MIDI in of the UM-ONE-MK32 interface, then connect that to a
computer.
 
  Roland UM-ONE mk2 USB MIDI Interface  $40
  http://www.amazon.com/Roland-UM-ONE-mk2-MIDI-Interface/dp/B009D3CTVS