We have been using Proseries professional for 9 years. I find it very easy to use. We have about 2500 clients, the only draw back is we have a lot of NYC fireman, cops etc... and they are so slow getting the 1127 available to use. Besides that, I really like the program. Included in the 2500 we have about 200 corporates, 100 trusts/estates and various other partnership returns and 990's.