I'm trying to figure this out...at what point would it be cheaper to train with CSC rather than sP at Riverside?

Felinah's stats are as follows: Level 181, Strength 447, Defense 453, Speed 453, Health 453, HP 453, Intelligence 304.

Currently it costs 8,145 sP per session and 28 sessions (which is what I'd get for the CSC) would cost 228,060 sP assuming the price doesn't change.

So when should I switch over to train by CSC? Which do you do?

Never since you pay with both. It's not an option.

Point of autotraining imo is to train faster, but it costs more

You need to start training with CSC as soon as possible. It'll charge the sP price there (228,060 sp in your case) and the CSC value (25). However, it becomes less worth it the higher stats your pet has, because you'll get less sessions in 24 hours for your money.

Oh...well damn. That seems kind of stupid. :/

My training time literally just went up, but I've been autotraining Flic (on and off) for a while on 8 sessions a day. When it reaches only 6 or less I'll probably stop autotraining.