It's worth considering that Howard Hill preferred a bit of string follow in his bows, and a rounded belly will tend to provide that, all the more so with hickory. There is nothing inherently wrong with that so long as you are willing to sacrifice a bit of pure speed in the interest of the other benefits that design allows. Personally, I am happy with it. If you are to, then so be it. If not, then feel free to flatten the belly and/or widen the limbs a bit. Either way, you should be able to make a fine bow.