Progress being made. I think I stumbled upon how to record the FX, AND get rid of the latency. On the aux track, simply pull the fader all the way down to mute the FX while recording. It's still present and recording but you won't hear it. I further discovered that I was able to record the built-in Pro Channel FX as well as third-party FX dropped into the FX bin. Now I can hopefully get rid of a bit of harshness as I record and not have to put an outboard EQ into the signal chain.
Actually, I spent some bucks last year and bought a Neumann TLM 103 and a "pro" preamp, UA LA-610 MkII, that does have some EQ tweaking ability but not in the range of vocal harshness. The UA has EQ on the extreme low end (200 HZ and lower) and on the high end (4.5khz and higher) but nothing in the middle where vocal "harshness" resides, around 1 to 2 k. I looked into trading it in for one of those even more expensive Avalons with sweepable EQs but thought I'd first see if I could tweak from within Sonar, and I'm glad I can. Hopefully the results will be pleasant to my ears.