Great questions indeed if planning on switching to a new phone. My experience is that it is all preference. Touch Pro is great if you like the slide out keyboard and landscape mode. Diamond is great for just the touch screen. I perfer the Diamond because I hate the slide out keyboard.
ROM's are made specifically for each type of phone, i.e. Diamond or Touch Pro etc... That goes with GSM and CDMA. DO YOUR RESEARCH AND READ AS MUCH AS YOU CAN BEFORE YOU DO ANYTHING TO YOUR PHONE. Upon Flashing, you will then develop this itch to do it over and over again. That goes with personal customizations. It never ends!
That is why this site and XDA are so great. Everybody is here to help eachother!
