I don't use subtypes (yet). But if you can have for instance a SLI-Te or a SLI-Si, then why couldn't you have a SLI that 'emphasized' or 'used more often' some non-ego function, like a SLI that 'used' lots and lots of Ni-role or Fe-vulnerable? Or a SLI that 'used' lots and lots of Ti-demonstrative? So that would be a SLI-Ni, SLI-Fe, SLI-Ti, etc.
This question is just sort of for entertainment only - I won't be able to argue much about it, it's just something I thought of. If you're able to notice or observe that somebody emphasizes one ego function a lot, it seems that you should also be able to observe that they use or emphasize other functions a lot, too.
Instead of using subtypes, I just broaden my concept of what that type is like. A SLI-Te and a SLI-Si are just another type of SLI.
(I don't use subtypes mostly because I'm still a fan of somebody else who doesn't use them, who shall remain nameless. But also I feel that they can sometimes distract people from somebody's true type - a 'SLI-Te' might actually turn out to be an LSE, for instance. So I'm not advocating that we *should* start emphasizing all the other functions too, like somebody using the role function a lot more than average, or whatever - it will just add more confusion.)