Business user-Return to Treo?

I'm a former 1st generation treo user-
After dumping my old Treo- I got the HPw6515 w/ 3" screen over the past 2 yrs w/ AT&T contract -but I am done with;
1) dropped calls
2) low resident memory(60MB) too inconvenient to move files to cards & many favorite apps liked to be on the res mem
3) slow/poor web access/interface
4) slow/poor email(re-reads all emails before downloading new ones)settings difficult to figure out as well..unlike my old treo)
5) poor call volume and now..
6) constant reboots(cover latch/microswitch probably)esp. w/ power below 40%

I may sacrifice 3" screen size and go back to Treo and get the Treo 750 - as it has good GUI and was very email friendly and now Windows Mobile etc..
Should I only consider 3G devices since internet/email speed is an issue for me. At&t's "At&t Tilt" or HTC Touch a better bet?

Any/all feedback on returning to Treo(750?)greatly appreciated before my HP w6515 brick dies..(wished iPhone was corporate/server friendly)

Thanks!
Tim