mooding to +res is worth it only on ninjas like mabui (due to the shields) in all the other cases +hp is better for tanking, unless you are sure that your enemy, like may happen in space time fights, will use mostly nin based ninjas, like edo hiruzen or angel konan, in that case too could be worth +res, but the difference is so slight that generally is not worth the effort.

if roshi is not mooded +hp flat out dies like in arena, except if you use him as move 1 and you have him so much stacked that it survives, but in all the other cases +hp is mandatory.