Sorry I misunderstood your comment and thought you were looking for the g500 shape with optical sensor. Therefore my comment was a statement
After I reread your post I see you meant you looking for a grip where you control the mouse between thumb and ring finger. In which case you may not need to only limit yourself to palm grip. I think you will find the CM Storm Spawn the optimal shape for that kind of grip.
DPI on its own is irrelevant, it only makes sense when you factor in the game sensitivity as well. People make a big deal about 400 dpi only because the microsoft mice ran at that and they have been quality mice for so many years. If they were manufactured at 800 dpi we would be making a big hoo haa about 800 dpi.
I run my spawn at 1800 dpi and my QL sens is 2. If I hypothetically could change my spawn to 400 dpi I would get the same cm/360 if I set QL sens to 9, or 3600 dpi at QL 1 sens. So the idea is that you want to set your mouse to the optimal dpi it tracks at and work around that.
I think in the past high dpi mice didn't track optimally at high dpi and as a result high dpi got a bad rep. In the Spawns case perfect tracking can be achieved at 1800dpi so lower dpi is pretty irrelevant.