Yes, starting with a 40' boat can be quite dangerous... the forces involved on a boat that large are considerable and can be lethal.
For instance, getting hit by the boom on a 16' sailing dinghy will hurt, but probably won't kill you in the case of an accidental gybe—getting hit by the boom on a 40' boat will likely kill you or put you in the hospital.
Another point is that the hardware and such on a 40' boat is just bigger all around, and that electric winches and windlasses do nothing for you when you're trying to haul the anchor out of the locker or bring the genoa up from the sail locker. Even the docklines, if they're sized properly, are going to be harder to handle.
Beth Leonard writes about such in her book, The Voyager's Handbook, 2nd edition, and clearly states how she felt starting on a smaller boat was advantageous, since mistakes were easier to recover from and the boat was more forgiving.
I would also highly recommend that your wife take at least an ASA 101 type course and learn enough to be able to singlehand whatever boat you get as well.
There have been several well-documented tragedies where the husband was injured, lost overboard, or died, and the spouse, not having the skill or in some cases knowledge to handle the boat resulted in nearly losing it. If you were to fall overboard, if your wife doesn't know how to operate the boat, it isn't very likely that you'll be getting back aboard anytime soon.
Sailing as a couple often means that you're sailing as TWO PEOPLE SINGLEHANDING THE SAME BOAT...even on shorter sails, this can be the case. Getting a boat that is too big for one of you to singlehand is going to be a problem IMHO.
Yes, definitely, I agree with you. I will start my ASA 101 instruction in a couple of weeks, followed by the 103. I am planning to do the 104 at the beginning of the next season. That is when I would be getting the Beneteau.
I am not the kind of guy who would jump into doing this without formal interaction/education. At the same time, I don't have a problem about practicing a lot before taking the boat relatively far from the dock, until I feel enough confidence. I just want to get the boat I like (or I fell in love I could say) and learn and grow with it.
What is your opinion? Do you think starting with the 40 could be dangerous or risky?