Hi,
I've played around with this a bit, trying to get a feel for what's possible and what's not. It's actually not as bad as I originally thought - but not that great either.

A 18F25K20 running at 64MHz, interrupting every 44us using DT-Ints slows down the PIC a fair bit. A 100ms pause in the main routine becomes 185ms in reality, a CPU load of 54%. At 32MHz it'll probably not work at all since all avilable CPU cycles will be consumed by the ISR and (mostly) the overhead.

The good news is that it does work using DT-INTS if you can run at 64MHz. The bad news is of course that any commands used in the main routine, that relies on soft timing, will be WAY off.

/Henrik.