I'm sitting here saying "why?" maybe I'm just not an intense phone user as you guys, but my 4G is still serving me well. My only complaint is the abysmal battery life (which with enough tweaks I've gotten to borderline-acceptable though it's a joke compared to my WM Intrepid which got 7 days of minimal usage between charges if I ran it down low) My only concern is that Sprint will be dropping support for the device and I already bricked 1 EVO and am sure I'll eventually do it again...
I will admit the iPhone has a better screen, but it's too small, I have enough trouble reading forums on my Evo (which are the primary sites I use since my bank and CC have dedicated apps).
Also as somone else said, and I concur, I HATE iTUNES! Especially when I can just turn on Samba and schedule file sync on my android devices... and organize my music by FOLDER instead of ID3 tag (which as most of my music is older and ripped from CDs, is not present or gets "automatically filled in" completely wrong...) For me the only perks of the iPhone are battery life and lack of crashes (and if your jailbreak then you often lose the latter)
And who says there's no pay wireless tethering on iPhone? Unless the 4GS broke it, there's MyWi (MyFi? MiWi?) which worked great in the short time I used a 3GS (though honestly I could never use it on AT&T due to limited bandwidth) but it does require jailbreaking. It does cost $20, which is rather high for an app but honestly, if your going to tether a lot, it's worth it's weight in gold.
I'm seriously curious what you all are doing that eats up the EVO's resources (outside of gaming, I know that's a killer)
Also, somone mentioned PSP games... I cannot imagine the pain-in-the-tail control scheme you'd have trying to play them on an EVO since it has no Dpad or major hardware buttons...