It doesn't matter if you are dealing with a bad LDS or a bad on-line experience. No two shops or on-line stores are identical. FWIW its great to have the on-line option for those of you who live in an area where there are no LDS, or the only one is a poor excuse for a retailer. For my money, I would much rather spend a little extra at my LDS and help them keep in business - why?
My LDS answers my tireless questions for weeks or months before I buy. Researches to make sure that a "redesigned model" is not in the offing (my one rule for them is don't sell me a major piece of equipment when you should have known that an upgrade was around the corner). He also is there to answer my questions after the purchase and trouble shoot issues (like when my new Mares IRIS reader wouldn't function). Fortunately since I bought locally I took the equipment and my laptop to the shop and we figured it out in no time. Sure glad I didn't have to try to figure that one out with an online retailer.
He also offers top notch certification courses (kinda hard to take those online), two charter boat dives a month (kinda hard to do that "virtual dive" thing), and a monthly club meeting of approx 25 - 30 local area divers. The meeting is the single best place to talk to divers face-to-face and really get the indepth skinny on equipment issues, diving experiences and travel tips. (no offense to the online forums but I can get alot more information during a face-to-face than via snipits of keystrokes). It also makes diving locally a lot more enticing as it offers the chance to hook up with a couple of different dive buddies so that someone is always ready to go out for the weekend that I want to dive.
As for the tank rental issue - do yourself a huge favor and buy a steel tank. You will enjoy the freedom of having it ready when you are, getting more air time, and carrying less weight. The only time I rent is when I am traveling via air.
Hopefully you can find a good LDS locally. Makes it really hard to get your tank fills on-line if you don't have a local LDS. (course I guess you could just go and buy your own compressor and fill equipment). Sometimes even a bad customer service LDS is a better option than none at all.