See BlackBerry Glossary - BlackBerryFAQ
. Sounds like your 8700, is personal. If that's the case and you are using blackberry data services (browser, email . . . ) then you are using BIS. (Or, you could be syc'ing to a company or a hosted exchange service, in which case you would be using BES.)
Only thing to do is go to the store and play with the sure type keyboard, handle the blackberry, see what you think. I used a sure type keyboard with my first blackberry and it was ok. Like I say, people tend to have strong feelings about it. You'll have to see for yourself.