I've been using the Treo Pro for 5+ months now and I am a happy camper. The keyboard took a little getting used to, However like anything else, Once you use it awhile it becomes routine. I found the stock browser too sluggish for my taste and first tried Skyfire and I am now using Opera.
I think the combination of performance and battery life are what really makes the phone work for me, I use it for light business use, Daily E-mail and texting and then I use Golf GPS for fun. I guess the bottom line is that the phone works really well for me.
I have been reading with interest about Custom ROMs, I have never used one, Wouldn't even know how honestly, However I will be interested to see how it works out when the new ROM's become available for this phone, It sounds like it is coming very soon. I have friends at work who have the Touch Pro/Diamond and they swear by their custom ROM's and they swear at their battery life with their phones.
Anyway, All in all a good solid phone, If I had it to do over again I would make the same choice and go with the Treo Pro.