To be honest, I simply walk over to LeisurePro if need anything (I work nearby). There have been other posts in ScubaBaord regarding LeisurePro and their practices so I decided to ask them which manufacturers are they authorized dealers of. The answer was an honest one ... none. They have provide their own warranties and, for that matter, service. In fact, they have a service department in back of the store (not too far from the elavator for those who have been there). ADORAMA/LeisurePro has been business for a while so their longevity probably is longer than your average LDS (I'm not sure what the average life is but I doubt if it's as long as ADORAMA/LP.
Perhaps some of their stuff is "grey market". They also buy closeouts from out of business LDS's. However, the majority is bought in bulk ... probably from the manufacturer. Do you think ScubaPro would say no to someone buying 100 fins or 50 regs? Some manufacturers won't sell to LP (case in point ... Halcyon) not because of service but because of the need to control retail prices.
What it comes down to is whether or not you are comfortable in buying "life supporting equipment" from them. LeisurePro is doing to the LDS what Walmart has done to ... Woolworth, 5 & 10, uhh Ames, Caldor ... maybe KMart post Martha ...
However, you can't get lessons nor dive trips from LeisurePro. So if you have dive store that needs to be supported ... then buy from LDS for certain items (e.g., big ticket service items). LeisurePro can't be beat for fins, masks, etc and other items ...
A quick analogy, I buy Pro VI golf balls from TGW but if I want new irons or woods I go to my local pro who can fit me and, perhaps, let me try them. The only problem I have is that my shafts rust at 50 feet....