Exactly. It really comes down to personal preference. I love the N42s in the Valk and I prefer both the N48 and 52 in the Illusion GTS.
I'm looking forward to hearing how you like the Thunderclap V1. I've made two, one with N48 and the other with N52. It can handle the stronger mags pretty well. I haven't tried the N42s in it yet. I might. I've got an extra one that hasn't been magnetized so I might do that when I get a chance.
You'll love those N42s from gaussboys. They're almost too pretty to use. Seriously, jewelry quality.
So I ended up receiving my magnets today, a bit earlier than I anticipated. Went out, bought some Gorilla Gel Superglue and went to town, except I got ancy and went straight into magnetizing the GTS. I don't really use that Thunderclap at all, just planned on doing it as a test cube in case I learned I absolutely suck at magnetizing cubes.
First off, you're right, these gold plated N42s are beautiful, and covering them in superglue that dries clear-white-ish and hiding them under caps really doesn't do them justice, but alas I bought them for their magnetic force, not their beauty.
As for my process I simply glued one magnet in a corner then the corresponding magnet in an adjacent edge, letting the magnets' pull do the brunt of the work of placing it (as in, I put some glue in then brought the magnet close and let go and it snapped into place, not precisely placing it with tweezers like I had originally intended, my roommate was in the shower and my tweezers were in there, I was impatient lol.) I used a fine tip sharpie to adjust a bit if need be, then put a bit more glue around the edge of the magnet, and wiped down excess glue if need be, like if some got on the outside edge of the piece where it could possible glue itself to another piece. Then I twisted the corner and repeated placing the other two magnets, using the adjacent edge's magnet as a guide. I continued on from there going all the way around, never placing a magnet without having its adjacent magnet in place to snap it in.
This is my first time using a magnetic cube, and I'm surprised that these feel as strong as they do after watching a few youtube videos that basically said, "Anything less than N50s aren't noticeable in a GTS," and being a bit worried (this is all after I already bought the magnets.) There isn't any audible click or anything, but you certainly feel when the layers snap into place when slow turning and you can feel the resistance when trying to lightly turn.
The cube's stability has been dramatically increased, as I expected. The GTS is a very unstable cube, at the tensions I use it would be able to sort of wiggle around and contort from cube shape just by applying a bit of pressure as I held it, and this has been almost completely curtailed by the magnets.
I'm still getting used to it, it's very strange after being so accustomed to its unstable, wobbly self. Also I'm quite certain that in the process of magnetizing it a fair bit of lube got wiped off from reaching in, pulling out an edge, or prying off center caps (I did manage to start bleeding under my thumbnail after prying so many apart, lol,) so I'll probably need to clean it out and relube it soon. I'm considering trying DNM37 again, the first time I put it in it made it absurdly fast and uncontrolable, which might pair well with the stability provided by the magnets now. I also got some Traxxas 30k in today so I might just use that instead, or both, who knows. Thoughts? I have 30k, Cubicle weight 2 and 4, Lubicle, and DNM37.
Thanks again for the tips, feel free to pass on any other industry tips you may have!
I used the 3x2 N35's in my Valk which have a pull strength of around 2kg less than the N38's, and I think they are too weak in the Valk. I do like the Valk M though it has been made better IMO, but it could be a bit better 
