i played the pre10-release over 300 ingame-days, had tons of money and an army of 100 knights.
the game crashed only once or twice, and it possibly wasnt the mods fault. there may be some minor bugs, but i cant remember exactly - they were unimportant for basic gameplay.
the new revision seems to be just as stable. it never crashed before, and everything runs smoothly, even with all those new features.
there are some bugs, but nothing crucial so far (a naked lord here and there).
theres no reason for concern, just go for it. the new battle-mechanics are simply awesome.