The 180s are, to my knowledge, the only 125mph hydraulic DMUs in the country - there's probably a good reason for that. Clearly the QSK19 isn't directly the issue as, even though these engines seem to have fairly negative press in every unit they're fitted to, 185s and 22x units don't suffer these continuous incidents. On that basis, fitting different engines to them probably isn't practical, they'd need a fairly major rework. DMUs typically lead shorter lives than EMUs anyway, and by the time something could be drafted in to replace them, they'd be very near end of life anyway. As I understand it EMR are using them as a stopgap before the HSTs are replaced with new build high-speed units? In which case if they show the same level of reliability on EMR as all their previous operators (and I see no reason why not), EMR will want to make sure they order enough new units to replace them all.
All that said, is it just me or does it seem like Hull Trains have a considerably worse time with their units than Grand Central? Given GC have twice as many it would seem like you should hear them having twice as many issues, but if anything, anecdotally at least, the opposite seems to be true.