Another Sabres fan here:
Regier is very good at asset management. His draft record is usually only as good as his scouting department. When the ownership made the change the video scouting his drafts were alot of hit and miss. He also swung and missed at several 1st rounders, though, most of that was right when he signed on (Heistein, Kriukov, etc)
He tends to overvalue his own players, which meant he usually would get a good return whenever he traded one, which was rarely. The life span of most of the players that made the NHL was until their UFA year. He was often times TOO patient, citing 'costs' as to why he didn't make any deals.
Best example was 2006 when the Sabres were coming off the lockout. It was pretty clear they needed another top 4 defensemen. They kicked tires, but refused to get anyone at the deadline. The Sabres lost in the ECF to the Hurricanes? Why? Because the injuries on defense depleted their depth. Another was 2000-2001, when Micheal Peca was holding out for a new contract. The Sabres held tight to their asking price. So much so that the rumors of what they were being offered was astounding. The biggest rumor is that he was offered Jarome Iginla, just before he started scoring 50 goals a year, straight up for Peca, which he declined.
I honestly think he's learned alot since then, but he does need someone over him to guide him and push him to make good trades even if the cost is high. The one thing I would be worried about is that he is a yes man. He will do exactly what is asked. So, if Maloney is too overbearing, he will simply get a copy of himself rather than someone with different ideas who will argue a bit about value of players, team needs, etc.