@uglybassplayer I've done tons of experimentation with string gauges and alternate tunings over the years. What do you want to know? Here's what I've learned:
Within a brand, a diameter makes a difference. Across brands (or types or at least factories) it doesn't tell you anything. Also, there are no rules. If you can get a tuning to work with existing gauges that's fine. Examples: for years in my instrumental band I would take a Sunbeam 105 and tune it to C, C#, D, D#, E, or F depending on the song. By C things get a little dull around the 11th-12th fret but it's a sound. Sometimes I'd tune my G string down to C or D.
For the touch guitar, the factory set comes with a .105 low Bb, which kind of sounds like ass, but I think they are making their strings too stiff. Other brands .105 or .110 sound fine at that pitch (technically B is the lowest pitch since open strings don't ring). So the same gauge and style (hex core nickel plated round wound) in different brands can sound totally different.
Only file the nut if it won't fit at all AND you are sure you're going to stick with the gauge for awhile. I restrung my Lull from BEADG to EADGC and did nothing to the nut, and it sounded great. Made a whole record with it and gigged it for quite awhile. It's still set up that way.
