This old chestnut again.....................
Like everyone says it all about personal preference and our circumstances are not all tranferrable into an amateur setting.
The biggest single one is to remove the temptation to hook out frames with the J. Its nothing to do with broken or rotten frames, its about what you can and cannot SEE when you shove that J under the lugs, or, as the junior staff are prone to do, worm it into the comb under the top bar and fish the frame out. Apart from the mess, and the annoyance to myself of seeing this done, we would lose queens at a higher rate. Sorry, you DO just lose more queens. Yes its possible to avoid this by taking longer and using more smoke in the lugs area, but why take the extra time when a perfectly good hive tool is already avauilable with fewer complications?
Secondly there is the apparently minor issue of strain injury. You will look at the J pattern and wonder what I am talking about, but the tool is marginally off balance compared to the traditional one and there is a slight tendency to twisting in the hand. We do not discriminate on grounds of gender or muscle power when choosing our technical bee staff. Twice we have had staff off with strain injury. The doc identified the J hive tool as the possible cause. Seem like nothing? try examining 70 hives a day, 7 days a week (ok, 6, they get a day off each), for 10 weeks continuously.
They are relatively inefficient as cleaning tools. I see people slicing away with the point end, of both tyes. Actually you keep the BUTT end sharp, and THAT is the fast cleaner/scraper. The other end is far slower and much more likely to raise up major splinters, which in haste have (occasionally) gone right into the beekeepers hand. The short end is as important a tool as the pointed end, and the J tool aint got it.
The traditional type are faster (saves money), safer, less damaging to equipment and combs, more versatile and have a variety of uses other than in the hive.