Well, I ordered the 18i6...  and it's all your fault, Beepster.  
 

AWESOME!! Lemme know how you like it.

I should have it towards the end of next week.   
 

Okay... just taking a little break now and thought I'd make a report on latency stuff. So it turns out last night I was indeed using the Zero Latency Monitoring function in MixControl for my bass track. After some wrestling with MixControl and X1 I got the Scarlett to monitor from X1. As I said earlier I left everything at default settings which was the 10ms setting in the "Settings" popup. It was reporting something silly like 50ms roundtrip at the time. I forget and I'm not going back to check. So now that I was hearing the bass being monitored from the X1 I was indeed hearing some of that latency. It was crazy but it was enough to bother me and probably effect a performance. So I opened up the "Settings" drop down in MixControl and pushed the fader to 4.0ms. This caused an engine stop in X1 (oops... I guess I should have closed X1 first). After I restarted X1 and reloaded my project all was good. If I REALLY strain to hear any latency I guess I can but it's pretty much right there. X1 is reporting Input: 9.0 msec, 398 samples Output: 13.0 msec, 575 samples Total Roundtrip: 22.1 msec. Obviously that isn't ultra low latency but I still have two more increments on my buffer knob (I'm not messing with that tonight though because I'm happy with the latency I'm getting). I have recorded and played back my project and there are no clicks or pops and the bass still sounds awesome. Hope that helps some.

BTW this signal is SUPER strong. I've got my trim knob on the unit turned almost completely off and had to pull my track fader in X1 WAY down and was still getting a super powerful signal. Sounds great. I can't wait to try out some of the included effects.

Thanks for all your ramblings Beepster. I'm using the QUAD-CAPTURE myself, but I'm pretty new to using external sound cards, and I'm finding some of your accounts quite useful.

Glad you've found it helpful, synkrotron. That's what I was hoping for with all this. When I first started looking at all the new modern interfaces it was very intimidating and confusing so I figured if I just put it all out there others like myself might find some meaning beyond all the technobabble. Cheers.

Anyway I wanted to make a quick report on latency results. The other night I plugged in my guitar to get some leads happening over top of the blues bass track I recorded. At the 4ms setting which Sonar was reporting a 22.1 roundtrip latency for I did actually start to hear an ever so slight delay. So I dropped it down to the 2ms setting and the delay pretty much disappeared. Again if I REALLY strained to hear a delay I could but it was really insignificant. Sonar reported just a little over 12ms roundtrip latency at this setting and again there were no audible pops, clicks or dropouts after recording or during playback. So that's pretty good. Not amazing but pretty good. I do have one more increment on the buffer fader (1ms) so I'd imagine if I switched to that I'd likely get around 6-7ms roundtrip latency. Certainly not the 2ms some devices get but those units generally cost a lot more. As far as the dry sound of the guitar it wasn't quite as impressive as the bass (a little flatter) but that might just be my pickups. I'll probably get much better results from my ART300 with the chrome humbuckers. I have not tried out the mic pres yet but that will be happening soon. I'll let you all know how it goes. Cheers!

It sounds like the minimum latency values do go fairly low if you're getting down to 1ms input.   But whether those values hold up under heavier CPU loads remains to be seen.   Hopefully I will know myself sometime soon since I should be receiving my shipment in the next few days.  
 

Yeah... I was a little worried about you, stevec. I know I may have steered you towards this but I realize now it is not a super low latency device. I did however achieve that 12ms roundtrip you said would be acceptable for you. I am running an i7 2600k with 16GB of RAM. I have to find a new BIOS inspector software or reinstall AISuite 2 to get a good look at what is happening with my CPU usage at these buffer settings. Really though everything looks good so far and I have put it through some semi rigorous experiments. From what I understand Guitar Rig is a pretty CPU intensive program and that is what I was cranking the guitar through (using the high samplerate setting) alongside unfrozen Session Drummer 3 tracks without any hiccups so that's probably a good sign. I really hope you can get it doing what you need because otherwise I would feel bad. Cheers.