The difference in profiles in hoppers, particularly the high end ones, is pretty negligible.
http://img168.imageshack.us/img168/6...tyfrontyr8.jpg
http://img168.imageshack.us/img168/8...itybacksc4.jpg
Taken from:
Loader Comparison - vLocity, Pulse, Halo, Egg, Revvy - PbNation
My stock Vlocitys cannot keep up with my stock Pulse. With a new chip, the VLocity could probably keep up with a stock Pulse, but I don't know as I haven't used an upgraded Vlocity. With an RF chip, I think that the only hopper currently available that could compete with a Pulse when it comes to speed and consistency would be a Halo with the Hater Symbio setup. That being said, the speed of my Vlocitys is good enough for most situations, and they're also noticeably lighter than Pulses.
-edit- Wow, I keep on forgetting how image tags don't work anymore. Gotta love the forum's progression.