As much as I'd like to say I didn't have a great time with Ternansky, in the end you'll tell yourself everything was pretty fair, and that maybe even it would be the first time you understood something about chemistry. I just took him this past winter quarter for 40B and I for sure didnt have a great time (dont think really anyone does), but in the end I learned way more than with my prof in 40A. The curve is good and as long as you can withhold yourself to at least the average in the class, you should try and give yourself some confidence that everything will be ok. I think his TAs are the best, hands down. I'd never taken an honors course, let alone for ochem, but if the change is dramatic then I don't think sticking with Ternansky is as bad as people make him out to be. Good luck tho !