I got the Signature BLA 002R mod, February 2009. At the time of this post it's been 18 months with it.
Clear Improvements:
-A/D convertors sound better
-D/A convertors sound pretty amazing
-It seems that the clock has helped with the clarity of the overall sound and "punchiness", but maybe that's just the convertors that I am hearing.
-Mixing has become much more effortless. Once I got the mod, I could hear how crappy my HS80 monitors were in my room. Bass traps and new monitors later, I trust what I hear 95%.
Not so sure about:
The 1-4 mic/line inputs seem to sound better, but boosting the volume knob is still troublesome. I ran a 1khz sine wave through each channel and it displays really well until the knob is above 12 o'clock. Once the knob is around 3 o'clock the sine wave displays even and odd harmonics that spike and clip the input!!! You can hear the clipping and see the clipping with an ITB RTA. The workaround is to use a separate preamp and/or channel strip and just keep the 002R input knob as low as possible (or completely off).
Inputs 5-8 sound the same to me as they did before the upgrade.
The monitor level knob causes static spikes on output 1 (left) whenever I turn the knob too quickly. It is annoying, and I fear it will hurt my monitors.
The headphone amp seems to be over 30db softer than it was before. It sounds much cleaner, no hiss whatsoever, and is a definite improvement. However, the loss of volume is, once again, pretty annoying.
Overall
I'd give the Mod a 4 out of 5. The price is pretty steep, but I do believe it is better to purchase the mod than to buy an external A/D-D/A (which is what I would have done, if not for the BLA mod). You get more for your money with the mod...
Hope this helps!