Do I understand this right? You were taught on an Air2 and your instructor did not cover how a standard inflator works? He should have covered how other gear works, especially since the other gear in this case is really the standard.
Air2's work for some people but many find them unacceptable.
I'll try to state this without starting the typical flame war but here are the advantages/disadvatages of Air2 type devices
as I see them.
Advantages:
1) You always know where your secondary is.
2) An OOA diver is likely to go for the one in your mouth anyway, it's wonderful that this is the one you plan on donating anyway.
3) No secondary dragging through the sand/silt/whatever
Disadvantages:
1) Increased taskloading when actually sharing air (dealing with adjusting your buoyancy using the thing in your mouth)
2) May not breathe as well as a good secondary
3) Probably won't get treated as carefully as a standard secondary attached to your $600 reg
An advantage many people cite is one less hose which means less drag. Persoanlly I disagree with that. Yes there may be
slightly less drag but it is negligable compared to other sources of drag (your wing, your trim in the water, the fact that you're not a fish to begin with).
The other advantages of Air2 type devices aren't unique to Air2's and can be had with different set ups without any of the disadvantages.
#1 and 3 can be addressed with using a standard clip to stow your secondary and practice deploying it. Before every dive, me an my buddy practice an air sharing drill as we decend so it becomes second nature. It only takes 20 seconds and it's a good habbit to get into anyway.
All of the advantages can also be had by having your primary on a 5 - 7' hose and your secondary on bungiee around your neck. Personally I feel this is ideal (and is absolutely required for some of the diving I do). The long hose is routed down under your right arm, up across your chest, around the back of your neck and to your mouth. When the freaked out diver grabs it out of your mouth, you simply duck your head down and while you are doing so, you grab your secondary with your mouth (or with your hand if it isn't rigged quite right). Now the OOA diver has 5 - 7' of hose to play with and that keeps them away from you. Another advatage is that unlike a standard length hose, the long hose won't end up behind you if its kicked out of your mouth. It will lay nicely on the right side of your chest.
I would recomend a 5' hose for a std OW rig, a 7' hose requires something on the right hip (usually a cannister light) to route the hose under to take up some of the slack.
A previous poster mentioned a flame war brewing over the Air2 type device... some people are very strongly against them to the point that they will not dive with someone who has one. While we, the air2 detractors, may be wrong on some points I've never seen a thread on SB saying that the long hose will kill you so unless you are fairly certain an Air2 is a safe alternative and presents unique advantages to the long hose/bungeed secondary I would suggest you consider saving yourself some money and go with the long hose.
Btw, one other advantage of the long hose: As you get some more experience under your belt and you don't want the dive master babying you, they will generally assume you are a competent diver when you have a 5 or 7' hose. This is because the long hose hasn't really penetrated the recreational marked and is still mainly used by technical divers. Of course if you are on the boat fumbling with you gear and you drop your mask in the water, the advantage was just negated
There are some good images of a long hose here:
http://baue.org/images/galleries/view_album.php?set_albumName=equipment
It's a DIR site, my apologies
