I've seen almost no benefits here but some hassles, as others have found.
Oddly enough, though, my favourite text editor recently had an update for registered users.
Since I first registered it (in 1993) I've changed both my home and office addresses and phone numbers.
I couldn't recall whether I registered it from home or from the office, or when, or if I used my own or my company name, or... Then I remembered an old file from the days when things were registered by mail or fax. I always kept a paper copy of these. In that file I found a copy of my original registration and submitted it, which did the trick.
So, in terms of a registration-benefit success rate that's about .1% thus far