70 sqm main, that's just coming into big boat territory...For me, the performance issues are greatly outweighed by the safety advantage and ease of furling from the cockpit. also the workload.
on my last boat, It took us up to ten laborious minutes to get the 700sq/foot main up with a 2:1 halyard and manual winch at the mast. Made me use the main only for longer passages.
I thought about in boom but the loads/friction on hoisting and the risk factor of having a super heavy boom made me favor in mast.
Although static stability suffers, i suspect that dynamic stability (inertia) of the heavier stick might help prevent inversions.
just did an atlantic crossing on a friends 2009 boat with a Marchal/Bamar in mast and we broke the boom. Having in mast furling was a blessing in that case.
Rare, of course but my point is that everything can break. Maintain ur gear and use caution when pressing buttons etc and take your choice.
Now imagine, you've switched to a furler and the furler is stuck, how are you going to deal with this mainsail you could barely raise before the furler ?
Why not just adding an electric winch to raise the main at the push of a button ? At least if it stops functioning you can still sail the boat... If the halyard gets jammed at the top (possibly worst case scenario), you can always send somebody up with the spinnaker halyard to cut it, if the main tears itself, chances are that you can get it down from deck etc... On a main you need to host, it naturally wants to go down so it is easier to sort out.