I think one of the reasons VVD has been so good for Liverpool is that with him in the side, and particularly Gomez alongside him, Liverpool can afford a high line because VVD has great recovery pace. With Maguire partnering Lindelöf, we can't afford a high line. Lindelöf has decent top speed, but a little slow on the turn, but Maguire is just downright slow. To me, it seems like Solskjær wants a high line as he wants the team to press high up the pitch, and then you can't afford a defence sitting too far back. For Mourinho, that would not have been such an issue as he likes to have his defences sat rather far back and then counter.
I think if we go for Maguire, Solskjær would have to revert to using Smalling alongside him to mask his lack of recovery speed. Then the question remains, is he that much of an upgrade on Lindelöf - I don't see it. As a pure defender, I don't see him as much better than Smalling either. From what I've seen, he seems to make more mistakes than Smalling does.
For 80m, I will be very pleasantly surprised if he is worth it.