We just started a new campaign and after much discussion offered the choice of 25pt buy & average hps or 4d6 six times with rolled hps. The guys all chose to roll and got a 20, 22 and 33pt buy equivalent characters.
I was worried about viability and offered a regeneration but they said no. The consensus was that they had wanted to take a chance with high stats and if they had got it they wouldn't want me to say they were "too powerful". Given that, they wanted to accept their characters and anyway I think their characters are all quite cool (they have become landed nobility at mid 1st level!).
NPC's in this campaign are generated with either 15,20,25 pt buy or the 4d6/rolled hps. NPC's get a default 15pts, PC-classed NPC's (and special NPC-classed NPC's) get 20pts, while leaders get 25pts. Special types get 4d6. Only PC-classed characters get max hps at 1st level.
The above set up is designed to recapture the specialness of good ability scores that, I think, Diaglo enjoys. I just want to have a few back stops to ensure the PC's get playable scores. So long as this exists for the NPC's, I think the players won't think twice.