@RumorConsumer there are some minor differences between the two and technically the MR52 may perform marginally better. The MR52 is a 4x4 array and so can use an additional signal path for MRC. But most clients are only a 2x2 or 3x3 antenna array, and so any benefit in one direction may be lost on the other direction.
If there is a benefit its going to be minor, and if your current experience is that bad then you are better of putting in another access point, its going to be a much better solution.
Also, keep in mind that the MR42 and MR52 are end of sale at the end of July - or sooner if Meraki hits supply issues. So you may need to consider what your next move is. Again, a Wifi 6 access point (MR44, MR46, MR56) may perform slightly better (due to some of the technical advances) but any improvement will likely only be minor and again I'd be suggesting you're better off putting an additional AP in.