I have the same setup as DAdams (above) --the 40c with regular and extended magazines, with a Veridian C5L and I have been very happy with it.
Unlike DAdam's 40c, which has Trijicon sights, I have Trulglo TFOs on mine, which I like best, but I have some pistols that came with Trijicon tritiums and I couldn't justify the expense of swapping them out. IMO, they're both up on top of the pack, with the Truglos being my first pick.
There have been a few prior threads on the Veridian, where I have compared and contrasted it to the the Crimson Trace, Insight, etc. I like green lasers (and sights) best, as well as being able to quickly switch my Veridian between my S&W, Springfield and Glock pistols, but to be fair, they all seem to have their individual strengths and weaknesses.
Veridian's scheduled to release a new laser/light that's a bit larger, with an even stronger tactical light, although the tactical light on the C5L is no slouch.
A couple days ago, I orderered, from Veridian, their new TacLoc 'autolock' holster for $49.99. I have used similar TacLoc holsters and feel they're fine and I like their adustibility, but this is the first that accomodates the S&W M&P series with the C5 series laser (C5) or laser light (C5L) attached. It can accomodate M&P's with 3 or 4 inch barrels, but not (yet) in 45ACP. It's been a while coming now after initially being scheduled for a March release and I am assuming they took that extra time to 'get it right'.
Veridian customer service has impresssed me.
Through November 1st, they have a promo where you also get 3 free Veridian CR2 batteries in the order and they offer a discount for military and/or police.
Optics planet and Amazon have had some good deals on Veridian laser, laser-lights and compatible Tacloc holsters and it appears Opticsplanet offers the new holster for $5 less & with free shipping, w/o the free batteries.