As with so many things, it depends on a lot of different variables that have to be taken into account before you can say one type of training will produce better divers than the other.
Where I dive in Puget Sound, the exigencies of thick wetsuit or drysuit for your initial training increase the challenge of learning buoyancy control. But the reality is that because of that, many people don't really learn it ... they muddle through a class, doing by rote with instructors who accept just enough to check the box on the list, because they don't really have time for "mastery". Will these divers do any better in tropical conditions? Not really ... because they never really learned buoyancy control in the first place, so using less exposure equipment will simplify their gear but it won't really help them control their buoyancy.
I think in this respect you have to put some caveats by saying that people who are used to diving in cold water ... or who were trained by someone who puts emphasis on proper skills development ... will have an easier time transitioning to warm water. But they have to show up with the skills at least modestly developed ... which won't always be the case.
Also consider environment. Puget Sound is cold, murky, and often can hit you with strong currents and large tidal exchanges ... this past week-end we had 12-foot exchanges, and later this month we'll have 16-foot exchanges. That much moving water presents its own challenges that you don't normally get in tropical places, because they just don't get those sort of tides. On the other hand, our idea of surf here is when the ferry goes by ... it doesn't in any way prepare you for the type of entries you might be faced with in some nice, tropical places like Hawaii ... where a mistimed entry can have you rolling in the surf zone wondering how you're going to get up and where your fins went.
On the other hand, I spend a significant part of my teaching time working with divers who are transitioning from warmer climes to Puget Sound ... and the most common complaint I hear from them is that they didn't have this much trouble learning buoyancy control in the tropics. Of course not ... wearing a drysuit means managing an additional, and significant, air bubble. Putting on a hood inhibits your ability to hear, and can feel more confining. Wearing dry gloves or heavy neoprene gloves removes your ability to feel anything with your fingers, and inhibits dexterity when it comes to manipulating your gear. And regardless of wet or dry, adding exposure gear inhibits your flexibility and means more lead to make it all sink ... and both of those issues will make even the simple skills you mastered for tropical diving more difficult ... until you learn new behaviors for dealing with it. And that takes time and practice.
It affects other skills as well ... one of the hardest things that people have to learn when they come here is that buddies have to swim pretty close together, watch each other constantly, and position themselves so they can stay in visual contact with each other. Either that, or prepare for a solo dive ... because if you buddy up like most tropical folks do, you'll be "solo" diving in no time. On the other hand, people who learn buddy skills in low vis conditions tend not to get lost or separated in the more user-friendly conditions of the tropics. They will, however, have to make some uncomfortable adjustments when it comes to going on guided dives where they're diving with several other people ... and that presents its own challenges to people who are used to only seeing each other during most of the dive.
And that's really the crux ... going in either direction requires making adjustments to different equipment and environment. Some adjustments are easier to make than others ... but that really depends on the individual ...
... Bob (Grateful Diver)
