Is it generally accepted that there is a superior process for keycap legends? For example dye-sub vs doubleshot.
Doubleshot is common for ABS and dyesub common for PBT, so it depends more on your preference of material.
The downside of dyseubs in comparison to doubleshots is that dyesubbed legends are not as sharp and, as I said earlier, you can only dyesub on keys that are lighter than the legend. Another downside is that colour accuracy and visibility on dyesubs might not be perfect if you're trying to make colourful legends, this goes especially for lighter colours. Normally these issues aren't too bad though, especially if you want to go with the classic black on white/beige.
The downside of doubleshots is that with each colour added you have to add another shot (which makes things far more complicated), so something like a smooth transition between two colours is not possible. There are some tripleshot caps, and I have seen a picture of quadshots, both are unusual though.
I'm not sure if you can dyesub ABS, I think the temperature needed to dyesub would make it melt or warp.
It varies, but generally ABS is better doubleshotted, and PBT better dyesubbed, because ABS can't be dyesubbed and PBT has warping issues when doubleshot
As I said I'm not sure if you can even properly dyseub ABS.
