The 32-year-old spent a spell on loan with the Gills as they unsuccessfully battled against relegation in 2008 and has now returned to Kent permanently after a year with Oldham.
Stimson has almost completely overhauled the squad since his appointment in November 2007 - just three senior players from before then are still involved - and Maher believes that has completely changed the club.
He told KentNews: "The change is remarkable really. I think credit to the manager for that, he's stuck to his principles and he's turned it around. No-one wanted to go down (to League Two) at the time but maybe it can work in your favour in the long run.
"There's a real buzz around the place now, it's massively different to when I was here last time. What you notice most is the hunger the players have.
"You see it in training when people want to do extra work and that breeds a good ethic throughout the club. Standards have gone up."