My wife's phone is still on EL30, but mine is on deodexed FC09 ROM and Modem, and side by side, my phone on wifi is faster (using FCC Speed Test) consistently than either 3G (we have the Airrave upstairs) or my wife's phone, and her's used to be consistently better (pre EL30) than mine. I think something in the modem was optimized since they put in Sprint Connections Optimizer software. I had stopped using wifi in my house because of the airrave signals, but now, even with only 2 bars of wifi, it is much snappier.
Ok PS: Now that my wife's phone has the update, her's is kicking MY @ss now. wifi in the same room separately tested, I get 5 she gets 8. It was reversed when we were both pre FC09 (I would get 3.5-4, she would get 5-6). Then i got FC09 and we reversed again, (my phone outperformed hers), now that we are both on FC09 she gets better performance than me again.