It's my understanding that, at the moment at least, everyone that's flashing ECUs on these bikes is using FlashTune. So you're really not asking for a review of SBU's flash, but rather a review of FTEcu's flash, as that's what they're all using unless you get something custom. If you mail in your ECU, it's all the same. (I'm open to being corrected on this, but this is what I was told, and my tuner goes directly to FTEcu with my questions.)
SBU's been really good to me when it comes to service while asking about and ordering other parts for this bike, but I didn't get my actual tune through them. I can give you a review, though, of my tune, which would probably be very similar if not identical. I have a 3/4 exhaust and custom fuel trim, but I think the real difference is in the TBW settings, anyway, as my bike is now buttery smooth coming on the throttle from a stop. It's still a bit abrupt coming off the throttle at low RPM, so I'm sending my ECU back to have the engine braking dialed down a bit, and I'm also going to have the decel fueling tweaked a bit to deal with a low RPM closed-throttle backfire.
Power is, obviously, much increased in the low and mid range, and it almost seems like it overwhelms the LIF control now, with the front wheel coming up quite a bit before it's corralled (even at LIF=3). I think this would apply even with the stock exhaust, so long as you wire the EXUP open and disable it via FT (exhaust does not buy you that much power with this bike). FT also disables the top speed limiter and gives you the ~10 hp back on top via allowing the throttle to open all the way. You can also disable AIS and air intake butterfly--I disabled the former and left the latter alone. You can also disable the electronic steering damper for running aftermarket and disable closed-loop and remove O2 sensors.
To sum up: Smooth on the throttle off the bottom (even in A-Mode), still abrupt coming off; angry gorilla power off the bottom, but not necessarily better drive off the corner due to the propensity to wheelie; ability to disable EXUP, AIS, intake flapper, closed loop, and e-steering damper. For a street bike with stock exhaust, the only advantage I can see is the smoother throttle at low speed. If you're not tracking the bike or swapping exhausts, just ride in Mode C on the street and save yourself some money. If you are tracking the bike or swapping exhausts, you'll probably want to find a local tuner, anyway, so you can dial in the fuel trim and have somebody to go to if it's not to your liking.
Oh, and these tunes are constantly being tweaked based off of feedback from customers and racers. Over time, the flashes will get better and better out of the box.