Magnepan, Ohm, Spatial or ??

@coot

I would expect to be able to tame that room using the adjustments right on the 5000s.
Mine are in an L shaped room.
Also what gear is upstream? That makes a big difference in resulting sound as well and most tweaks as well.

I had Maggie’s, replaced with large Ohm F5 s with 12” drivers. Have heard Spatial at shows. Both are viable choices. Ohms work very well in odd shaped rooms. Biggest difference is Ohm will have the large sweet area and may be easier to place for good results whereas Spatial specs as somewhat more efficient and is probably more flea power tube amp friendly though beefier  tube amps seem to do well with Ohm as well.

@mapman Upstream gear is my PC feeding FLAC to a Topping D70 DAC and then a Jolida 1501RC hybrid amp (100w).

That amp should do quite well with either I would expect.   For me getting the right speakers to fit the room is job 1, then amp match job 2.   
The thing the Ohms do uniquely is the very large sweet area.   They will do soundstage  and imaging coherently throughout the room with most any decent placement.  Spatial will be tougher placement I expect. Both sound great when set up well. 

@mapman 

It would be great to demo both of them.  I talked to John at Ohm.  4-5 months for delivery!  Not sure how behind Spatial is...

@soundchaserh
They are ISO-Acoustics’s Gaias and they are an amazing upgrade. The M3’s perform fantastically with any music IMO.