https://www.spritdesigns.com/product-page/box
As long as you don't mind swapping the springs out yourself...
Have you encontered any issues with your Sprit 100g? How long have you used it for? Would it crack the plastic because of too much force?
I don't think that's possible. I have some 90g springs, and they still feel weak. I can barely tell the difference between them and lighter (eg. 75g) springs. As in, yes, I can tell the difference if I compare them side by side, and I wouldn't want to use them for my alphas, but they still just feel like regular keyboard springs (ie. easy to press even with a pinky). I think you'll have to go waaaaaay heavier before you need to worry about anything getting damaged.
I put a super heavy spring into a switch once out of curiosity. It's just a spring I found in a drawer - no idea where it was originally from, but it definitely was never intended for switches, and was a bit larger. At a very rough estimate, I'd say it was maybe 450g? You could rest your palm on it and it wouldn't budge; to press it required actual physical effort. I might use it one day for something I really, really don't want to hit by accident - like a reset firmware key or something. Anyway, that one felt like it
might do a little damage to the switch in the long term, if I pressed it enough times. But maybe not even. The switch certainly managed it with no problems for the day or two I had it in, and that spring was on a whole other level than any 'normal' springs like 90g or 100g.
