Not sure what I would use the quarter round for, personally. I got a couple of fret end dressing files for free when I ordered a different crowning file from a guy on eBay (more on that in a sec), but I think if I had to consider buying one, I'd just get a set of needle files and grind down and polish one edge to be smooth -- same end result, and needle files are much cheaper.
For crowning, if you have the money, get a nice diamond one:
stewmac offset diamond file
They're incredible to work with.
I bought a diamond file on eBay for about a third of that price...however, despite being listed as having medium and jumbo sides, the medium was still not really well shaped for medium fretwire. "You get what you paid for" kinda applied there. When I did a fret job for a friend, I sprang for one of stewmac's standard double-edge files
stewmac crowning file
I got little chatter on handful of frets the first time I used them, but it doesn't take long to learn how to avoid that. And it was never anything that couldn't be buffed out with 220 sandpaper.
So, personally, I think the 1/4 round is pointless. But I don't do enough work to know if there are situations where guys rely on them.
If you're going to recrown frets, get a proper crowning file (standard or diamond), or go hardcore and learn how to do it the old fashioned way, with a normal (3 corner) file...
I suggest you skip the fret end dressing file until you've done some work and can tell if you need/want it. You might find that it's not worth a $15 file, or that you can't live without one.
As for the 3-in-1 -- I've never used one, but have always been tempted. I'd be concerned about how tightly the burs lock in place. And the offset handle is nice, but the offset diamond files are more helpful, I think. Most fretboards are radiused, so when you are near the ends of the frets over the body, you're filing at the body. So the straight end of a file is going right at the body -- and you just have to be careful (or cover that part of the body with chipboard or tape). The diamond offset files have a curve at the end, so it's easier to keep the cutting surface on the fret while you roll the file up and away from the body at the end.
Good luck!
ltt
