I almost went with the RME but ended up with the UAD because of the plugins. I may eventually get a RME Fireface 802 to replace my VS-700 but I needed a temp fix and I'll still keep the UAD around for the plugins.

Jim Roseberry
The UFX can go down to 4.3ms total round-trip latency at a 48-sample ASIO buffer size (44.1k).
That's the best you'll find in any USB audio interface.

Have you tested the Twin? They're claiming lower latency than that. Of course it also does the near-real time processing with the UAD plug-ins. I'm very interested in checking it out in depth...

Craig,
 
The almost real time processing with UAD plugs is amazing... the delay it is so slight that mere mortals can't tell the difference (me included).  Great for guitar work processed with the amp sims.... sounds good too.  So good that you will be tempted to lay down your tracks with the UAD amp sims directly into SONAR. The AMPEG ams sound GREAT with BASS.
 
I still split my guitar signals with a DI and record the DI along with the processed sounds just in case though.
 
Jim

Thanks Zargg for the update on WIN 10.  I might make the leap. I am using 2 PCIe cards (Quad and Duo) as well as the silver-face APOLLO unit. 
 
Can anyone confirm the silver-face compatibility non issues?
 
Thanks,
Jim

UA now officially supports Windows 10 with Apollo Twin USB as of UAD v8.6
I just got an Apollo Twin USB. Just getting started with that and Sonar Platinum.

Anderton
Have you tested the Twin? They're claiming lower latency than that. Of course it also does the near-real time processing with the UAD plug-ins. I'm very interested in checking it out in depth...

Hi Craig,
Realtime processing of UAD effects is <2ms.  
Total round-trip latency (monitoring thru host DAW software like Sonar) is ~6.5ms
Haven't tested extensively (want to measure the noise-floor)