I've been happy with my visor neo so I think you'll be happy with the edge. If you do find you are running out of room, you could start using the sled and get a flashplus or memplug for further expansion. That was the driving force for me with the visor over palm or sony. I picked up a 56K modem a couple months back for $10 and just purchased 4 targus stowaway keyboards for $5 a piece. (unfortunately they do not work with the edge or prism) For me the biggest drawback for the sony was the batteries. I change out my rechargeable AAAs once a week (I tend to take it outside a write reports on it at the picnic table) which isn't too much to be annoying but on my travel days and some weekends when power isn't readily available for one reason or another, being able to toss in regular batteries to keep the thing running is nice.
Enjoy your purchase.
BTW I have 6.5 meg in memory and another 45 meg on the CF card. Works like a champ.