psion with infrared mobile handsets

[mandala]

This group has been a great resource to me in the past. I have used the
Psion 5MX to e-mail with various handsets in the UK and the US but only
because I could find the keys to the kingdom through other psion users.
I want to get a new handset and wanted to find out if anyone has
experience setting modems/initialization strings/psion updates needed.

I am looking at the only handsets I know of that have infrared
available in the US. There may be more, so if there is something else
on the shelf, I would be happy to hear about it. The ones I know about
are:

Sony Ericsson W800
Audiovox 5600
Sony Ericsson S710
Samsung P735

Thanks,

Mandala