I can vouch that the Sound Quality of the mic pre-amp varies wildly from interface to interface.

My cards I've had during my PC based home recording years, and the reasons I've changed:

Sound Blaster AWE - no mic preamps
Changed to the next in line to have front-of PC connection

Sound Blaster Live Platinum
Changed to the next in line to have in-built mic preamps and move between desktop and laptop for recording PCs at will

PreSonus Firebox - 2 mic preamps that were pretty noisy
Changed to the below because my laptop with firewire became my only recording PC and it died, and laptops with TI firewire chipsets were then astronomically priced

Tascam US-800 - either 6 or 8 really clean pre-amps but the worst driver software ever written for a soundcard.
Switched for more inputs so that I don't have to patchbay anything, or swap-in/out and to just plain get rid of that Tascam US-800

Focusrite Scarlett 18i8

The Scarlett 18i8 seems to have pretty clean pre-amps.

As for needing your VTB-1, you don't need it with the MOTU as 90 dB stated above.

The MOTU should hold it's value very well. I've had my hands on MOTU stuff but never had the right amount of money at the time. One thing that might be really useful to you is that it can be used completely stand-alone as a line mixer. You never know when that might come in handy. Just one such example: If you ever play out with a small band or sit in but can't take an amp and need to rely on amp simulation, then you should be able to use this for a 'more me' monitoring mixer if the FOH engineer will give you a copy of his main mix. The other nice thing about MOTU stuff is that they have proper VU meters on all the inputs - this is still unfortunately rare in I/O devices.

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