Maybe worth noting that SiC dies are
tiny. The current density can be impressively high; or, not so much the current density but voltage (SiC is a bit worse than Si on mobility, but several times improved in breakdown voltage), but you see the product of both as switching area and power dissipation, of course.
That's not to say the power ratings are pitiful. Equally impressive is the thermal conductivity, so, as long as the chip can be made quite thin, and the backing plate is solid copper (or maybe AlN), overall power dissipation can still be reasonable.
(I guess that means I don't actually have a point, then.
It's fascinating, though.)
I haven't looked at them for linear purposes before; the usual SOA warnings apply, of course. (I gather the JFETs generally offer fairly unrestricted SOA, then? That's nice.) I would guess for most purposes, the lower cost of Si will dominate the decision, but I wonder if the lower capacitance offers higher bandwidth for certain applications? Could be a performance edge that way, for the same reason it's an edge in switching applications.
I don't know that cascodes wouldn't track well; they're certainly not going to be worse than discrete parts on a common heatsink. Arguably maybe even better, as the bottom transistor doesn't suffer from self-heating, maybe even its RthJC is better than the Rth(J1-J2) as it were. I don't know offhand how they're constructed (two die pack? stacked? surely they're not monolithic..).
The biggest, disappointment I guess, and more generally, is the kinda failed promise of high Tj(max) -- they're limited by packaging materials (150-175°C) same as everything else in plastic. So the only exceptions are the few metal and ceramic packages (mostly MIL spec $$$). That said, it's not necessarily a big loss, as some MOSFETs (JFETs too maybe, not sure offhand?) have truly abysmal tempcos up there (like 4-5x Rds(on) at 300C or something, I forget how bad exactly?). But some others are fairly flat and I'm not sure what the difference is (SiC allotrope? transistor design? just more substrate thinning to remove internal resistance and accompanying tempco?). Anyway, that's not a comparative thing, just a reaction to, earlier hype I think. Overall, compared to Si, modern types at rated temperatures are indeed as impressive as their specs show.
Tim