MMA will hugely increase your ability on the ground but try to absorb the principles into your nastiest taijutsu rather than changing your entire art as soon as a fight goes to the ground, because of the sports aspects and subsequent limitations will be a problem otherwise.
Training against MMA and BJJ cross-trainers is also good for your taijutsu because they will exploit openings that we often don't take into consideration.
In my experience most taijutsu practitioners consider the fight to be virtually over when an opponent is taken to the ground, and often don't bother tidying up or finishing off, as the focus is on avoiding the intial attack and taking them down, but in the mindset of the modern grappler the point at which many of us consider the fight over is to them the 'beginning' of the fight proper. This was struck home to me recently when
I performed what we had been practicing with aplomb, but when I went to finish I left an arm outstretched for a split second and my uke, considerably junior to me in taijutsu but a cross-trainer in BJJ, had me locked in one of those upside-down armbars before I could react.
Something I now try to do is not throw uke onto their back or allow them to roll onto their back, because a lot of these young chaps will go quite willingly into what they call the 'guard' and you follow them to the floor at your peril if you allow them this advantage.
Kind of bizarre when you consider the rules of Olympic judo, where exposing your back is fine but being rolled onto your back (into 'guard') indicates a loss.
