I had a couple of years experience with a tablet in the field, I had Wintotal and Apex at that time. I think because tablet sketching takes longer than hand sketching, and because I was quick with the software at the office, there was no time saved in that regard. Also, the data re-typing was saved, but other new tablet tasks caused the time to be eaten up, like opening the file on the tablet, and downloading the file at the office. Further, a lot of the re-typing we are talking about can be done super quickly on todays software, so your really spending a lot of money to save only a little time.
To be fair, others think its saves a lot of time, maybe they will chime in.
In my opinion, if you are going to do it, the real benefits would be the ability to keep working when you get stuck out in the field between two appointments, and to pull comparable data from the field (at the additional cost of internet access).