Downside: All judges will probably move prisoners to the hole (the oubliette thing you describe), making it harder to escape than already is.
I think few Judges will opt to move them to the 'House Arrest' kind of thing, to be honest.
That can be leveled out by limiting things or upping the costs.
perhaps limit the oubliette to only one prisoner, and or make the oubliette cost allot of honor.
Nobles where ussually threated very well in prison back in those days, holes are for commoners, not nobles.
Also limiting the oubliette to banned nobles only would prevent new players to end up with characters cut off from the game.
Any attempt to make prison (and especially getting wounded) less restricting the game is very welcome i think.
