So trail riding the winter fat off my gelding with the "xl cinch" and said fatty spooks and spins causing the saddle to slip. I kick out and jump off. Later I was told I should have dismounted on the opposite side of the way the saddle slipped. That would have had me dismounting on the off side. I did not want to chance that. So which way is better to come off the same side as the saddle that is slipping or the opposite side, even if its the off side? Would it make a difference if english or western saddle?
If a saddle is slipping I think you should get off asap in the safest manner possible. Getting off on the other side makes sense but if you aren't equally as comfortable dismounting on the off side then you could have ended up with a twisted ankle or under your horse if you didn't land on your feet. Personally I would be more worried about why my saddle slipped then what side I got off on. It sounds like his winter chunk has affected his saddle fit or he was calling your bluff and your cinch wasn't 100% tight. A spook shouldn't shift a well fitting saddle girthed up correctly. Then again, if he's chunk the only way to get the weight off might be with a saddle that is fitting a little funky till he trots the pounds off.
I have saved a slipping saddle on the pony when he was being a jerk, I turned him towards the falling side and made as if to dismount to the outside of the turn, foot in the stirrup, threw my other leg over and away, cetripital force dragged the saddle back over and a fast remount kept it from going over that side too. At the time we were moving through the grassy with trees hillside too fast for a safe dismount, it was the only thing I could think of.
I would definitely not recommend it as a regular practice, time to see if horse is losing weight, not fitted properly etc.