I'm in the process of writing a new dry suit manual.
For the truly experienced diver making the jump is possible without professional instruction. Although I have had warm water trained instructors contact me about classes after they gave it a shot on their own. For a newer diver I think it's essential. You may be able to find mentors to take you through the process but there comes the liability aspect of it for them. If they show you incorrect procedures or if your survivors think they screwed you I would not want to be them.
For a new diver there is enough of a jump in skills and knowledge that I strongly recommend you get professional instruction. I don't know where you bought your suit but when I sell one a dry suit class is part of the package. No extra cost for those able to take advantage of it. Classroom, two pool sessions, and 2-3 open water dives. I can't believe any LDS would sell you a new suit without offering training. Wait, sadly, yes I can.
As for using it as one dive on the AOW or AA dives I think that is going to get people hurt. No pool, no real classroom, just one dive in a likely ill fitting suit. Total BS.
At my local dive school, pretty much all the training is done in drysuits. The only exception is if somebody is an odd size and they don't have a suit to fit them, but wetsuit diving is only really possible certain times of year. On an AOW course, drysuit is an option for one of the adventure dives, but the remaining dives would also be in a drysuit.
Very few divers I know have the drysuit speciality as they are taught from day one open water in a drysuit. I have the drysuit cert because I was doing upgrading from the PADI Scuba Diver I had done overseas. The dive school said that although I only had to do part of the course, I was welcome to sit in on the full course as there were others doing the course. For the OW dives I had already done, they said I could come along if I paid the site entry fees and air (the school pays this on the OW course). I enquired about doing the drysuit speciality on the extra day as I was under the impression I would need to hire a suit for my early dives. The cost was very little if done at the same time as OW, however, I never needed it as I ended up buying suit straight away. I was of course able to use it towards my AOW.
I was amazed today to find out all my instructors are voluntary and don't get paid, yet the owner of the dive club/shop drives round in a evoque
Mike
I've never heard of instructors working for nothing, but I doubt it is much. Of the instructors at my local school, we have the head of compliance and risk at a university, a senior IT professional at a multinational computer equipment manufacturer, and the director of an electronics company. I therefore doubt any of them do it for the money. DMs are not paid, but instructors are. I don't know how much, but I imagine it cannot be much.
An OW course is £375 and typically there are three students, so that's just over £280 a day. Out of that there are equipment costs, pool hire, upkeep of the building, PADI's fees, course materials, public liability insurance, site entry fees, air fills, transport etc. I doubt after all that is paid for, there is much more than enough to pay minimum wage, and when you consider most instructors will put in extra time with students who struggle a bit for nothing, they probably get less.
An issue we have in the UK that other countries don't is the Diving at Work Regulations. They say that in addition to the instructor, there must be a safety diver in the water and shore cover. Usually the safety diver will be an unpaid DM or rescue diver and the shore cover will be a club member. If it wasn't for them doing it for free, the daily wage bill would be over £150 a day.
If the school was to pay all the staff, they would have to put prices up. This would put prices up because it is guaranteed somebody else will do it much cheaper. Either that or people will book a cheap holiday in Egypt and do the OW course there, or join a BSAC club for around £250 a year and get trained for free by volunteer instructors.
My dive shop of choice offers all the usual PADI courses and the OW is just slightly dearer at £399. Most of the shop staff are instructors and I have often seen them running courses at the local muddy puddle. As these are his full time employees, I expect they are being paid properly. He has told me before that there is little profit in courses, but he would be daft not to offer them as it gets people in his shop buying shiny kit.