What an interesting question! I currently deal with three different LDS's. They are all full service shops but each seems to have an advantage over the other two in certain areas. I'll give you some examples.
Dive Shop A: This is where I go for training. This Dive Shop has a very competitive (not cheapest) price for their training classes. Their training prices are all inclusive so, what you see or are quoted is what you pay. They also give you, in my opinion, a good, solid education. The dive environment that they train you in is interesting and closer to what I actually dive in than what the other two shops use for their training classes. Equipment prices are about the same as the other shops but since they are the farthest away from me I don't buy much from them except training.
Dive Shop B: This is where I go for charters. This Dive Shop handles their own charters so can set me up with a charter and rental equipment all in one place. I don't have to run all over the place to get my equipment from one source, and then get to the charter in another location. In addition because it is all coming from the same location I don't have to pay for a two day rental of equipment as I would if sourcing from an "outside" LDS. This saves me money and a lot of time. While Dive Shop B has training prices similar to Dive Shop A I haven't used them for training as I am not a fan of where they conduct their training nor how they "present" their course costs (see Dive Shop C).
Dive Shop C: This is the closest to me. They are very nice people, very helpful. This is where I have bought the bulk of my equipment from. Their prices for equipment are a little higher than the other two shops but they are a LOT closer so the savings in fuel make up for it. Their training prices however are very expensive, almost double the other two! I particularly don't like the "nickel and dime" approach they take towards training fees eg. X dollars for the class, Y dollars for the course materials, Z dollars for rental equipment, plus the certification fee, entrance fee to the Open Water site, etc, etc. Please, just tell me how much it will cost me up front. I don't like surprises! Dive Shop B also does this. Dive Shop C also uses the same location as Dive Shop B which is one I am not fond of.
All of these shops have nearly identical training programs, all offer foreign travel packages, equipment sales and access to local dive sites. However, they all have different approaches. Some of which appeal to me as a consumer and some don't.
If I were to give your friend some advice it would be:
1) Make sure your training course prices are all inclusive and not excessive for the area.
2) If you are going to rent equipment for people to use on charters charge a one day fee provided they pick-up and return the equipment within a specified time frame.
3) As long as your equipment prices are not excessively high you should not have to much trouble with the internet. I bought my equipment from a dive shop as I wanted it to fit correctly and to have a relationship with someone should I have problems with it.
4) Make sure your training site is able to accommodate the needs of divers at different levels or have a different site for the more "advanced" divers.
Well, that's my two cents worth. Hope it helps.