I haven't actually done much with them as yet, but no problems have cropped up at all in the little time I've had to play with them.
Lockups on 5300s never required any fancy add-ons in my experience. Have you tried to duplicate your results, without the MV16-EN on board. I wouldn't be at all surprised if you could, what with the 5300 being the very first PPC implementation in a PB and all.