Yard Guy wrote:

Am I to assume that there is a debate regarding these propane-powered traps,

Not that so much as many cant seem to grasp that by their
nature they are going to be quite dependant on the wind.

With that sort of variable, its not surprising that few can really
grasp the basics of when they work well and when they dont.

The other complication is that counterflow traps work a lot better
that traps that dont have counterflow as well as the propane.

and if by the sake of their operation they end up attracting more
mosquitoes to an area than would ordinarily be there in the first place,

That wouldnt matter if they then trap the mosquitos effectively.

and that they may not capture these excess mosquitoes,

They should do that if they are well designed.

thereby making the mosquito problem worse for the backyard the unit is located in?

There is no evidence of that. Like with anything tho, some work better than others.