I played with a 50" driver for a period, then down to 48". I was a small scale LD guy, could definitely knock the letters off a ball, but never had the money to try to take it further than local events.
I used one for about 3 seasons of actual golf. The advantages are pretty awesome if you can hone it in, if you aren’t a smooth swinger, it can lead to some hellacious misses too. I’m now using a 46in driver and I still catch the occasional bomb, but stay in play better. If I knew I would be playing a lot of scrambles I'd try to get back to the LD clubs.
I had some opportunities to score that I’ll never see with a shorter driver, like putting on my second shot on a par 5 ((dog leg I was able to cut), but I also am far less prone to losing a ball now. I think the longer shaft can help a lot of people, if they take the time to learn the swing. Longer actually felt really natural to me, I took to it like a fish to water. I gained an obscene amount of distance without a huge sacrifice in accuracy, because I was never accurate anyway.
If I ever make time to practice again, I’d probably move back to a long shafted driver in my bag and either keep a standard driver in the bag or just move to my 3 wood, which isn’t unreasonably far behind my normal driver. Without practice, it’s easier to use the "standard" driver length.