T-Mobile Dash (HTC) nice try falls very short of the mark.

HTC Dash Review - tested with MacBookPro (OS/X 10.4.8) -MissingSync for Windows Mobile

Shortcomings that disqualify the phone:

The main disqualifier: TMobile has broken the ability to transfer data via WiFi using typical apps such as Internet Explorer and email. One must use GPRS/Edge.

Since each time I have traveled abroad for the past five years, I have not been able to use my T-Mobile account abroad despite having gone thru the tech support fire drill prior to each departure. The walk you through unlocking the phone and enabling international roaming privileges. Yet, on arrival, nothing works at all. Yes, I know how to switch GSM carrier networks manually. Since the past is often a reasonable indicator of future performance, I have no confidence that even if was inclined to spend an additional $30/month for antiquated and slow GPRS/Edge data connections, I would not be able to use the device abroad for data access. In the past, the only way I could use my phones was to buy a local chip and put the TMobile SIM in my wallet for the duration of the trip. Even if TMobile was present, for example in England, it was still unable to roam, even after an entirely wasted day at the mall in Manchester with inept TMobile people who wanted me to call the USA office on my own dime on a phone that would not work. You get the idea, a typical SNAFU.

Other nagging problems that made me want to hurl the phone to the floor and smash it to bits: ;-)

2. No notepad or text editor. Must set up an email account to edit any text. Even then, there is not a cut and paste feature. You cant even select text. Brilliant! I had to manually type in WEP bin hex key despite having transferred a text file to the phone to copy the key from on the phone. The text file was NOT able to read by ANY app on the phone. It is a standard Unicode text file readable by any platform anywhere except of course for Microsoft.
3. You can’t set up email without paying TMobile even if you use your own WiFi access point at home. USB email sync does not work on Mac, at least with Mail or Thunderbird. Did not try with Entourage, but I do not wish to use Entourage, a terrible program in terms of standards based messaging services.
5. Infrared on phone does not exist. A myth. A nasty myth.
6. Direct Push and Data Connection both require TMobile based services and preclude WiFi based Access. This issue prevents using any email service without TMobile provisioned datacoms. You can use Push with Outlook, of course that only exists on Windoze, and requires that you connect to your computer. Checking email while mobile is not practical as a result.
7. WiFi reception is poor. And the questions remains of what you can actually use WiFi for anyway given the main shortcoming above!
9. Volume touch pad just stinks. Unintuitive, unresponsive, and if you don’t read the manual, you will wonder what that is for, and why the volume randomly changes.
10. File system browsing (Start Menu etc) is incredibly slow.
11. Browser is just plain useless. Can’t connect except via Tmobile services.
4. Mac issue - Bluetooth connection malfunctions. Cannot pair with Mac either direction. Pairing from phone does not illicit pass code response on Mac. Pairing from Mac finds the phone, succeeds in pass code response handshake then finds no usable services (like OBEX or other BT protocol apps). You can "beam" a file to the phone via BT, but that is all.

1. Using Missing Sync App for data sync -
a. Only able to sync via USB cable. Bluetooth sync attempts time out halfway thru the connection.
b. It took nearly 45 minutes to put 1200 contacts onto the phone, first sync. Second sync hung and was not able to be recovered.
c. USB cable not recognized without reinserting each time. App does not detect the presence of the cable-connected phone unless cable re-inserted.