I think that you have gotten good basic answers. I have been researching this for my 38 foot boat for several years now and I am actually working on a draft paper on this topic. Here is the gist of the info that I have gotten from a couple different lofts.
Laminates need to be handled more carefully. They hate sun, flogging and careless folding. Lazy Jacks and sown in mainsail covers are an absolute pain in the butt with laminates because you can't flake sails properly with the Lazy jacks rigged so you either shorten the life of the sail, or increase the work dramatically. Laminate sails come in all kinds of flavors. The ones that made sense for my boat are as follows:
Film sails (3dl's and the like) have a performance lifespan around 300 hours but they still look like a sail for a very long time after that.
A properly made arimid/mylar sail, which has been reasonably protected from UV (religiously using sunscreens or socks and sail covers) and which has proper chafe patches and handling, has a performance lifespan of closer to 1500 hours and will still look like a sail after several times the number of hours in its performance lifespan, but on big genoas just will not have the racing performance of a film sail. Polyester/mylar sails have a shorter performance and overall lifespan than a aramid/mylar and will offer significantly less performance than aramid strands in changeable conditions. Dacron has the shortest performance lifespan of all of the choices, perhaps a few hundred hours, and significantly offers the least performance at both the high and low end of the wind speed range. Dacron is a little more forgiving of chafe, UV and much more forgiving of flogging. Dacron has a white triangle life probably in the 4000 hour range and if treated as carefully as you need to treat laminates, might look like a sail considerably longer than that.
In a general sense, laminate sails don't stretch as much in gusty conditions and are therefore much more forgiving in terms of speed, heeling, powering up at just the wrong time and that helps with control and seaworthiness. They are generally lighter in weight and so hold their shape and therefore perform better in the lighter wind end of their windspeed range. In other words, for a given sail size and shape a laminate sail will have a much wider windspeed range than a dacron sail and so you can get by with a smaller sail inventory. (T34C- That's the good news
Also T34C's comments about mildew only seems to apply to sails with taffada elements. I have not experienced it at the seams.
BUT as everyone said above there are huge variations in quality from sail loft to sail loft, and even in individual sails from particular lofts. 20 years ago I considered buying a boat that had an entirely kevlar sail inventory. The owner gave me a survey for the boat, and in it the surveyor said words to the effect that no one in their right mind would go cruising with Kevlar sails. My boat came with a nearly 20 year old kevlar/mylar sail that I used in heavy going and throughout the winters and which finally delaminated and tore leech to luff in a 40 knot gust when it was roughly 23 years old. After doing my reseach I have concluded that Kevlar/Mylar is a less expensive way to go for performance cruising on a boat the size of mine and way cheaper for racing. I can have fewer sails in my sail inventory and those sails will continue to perform longer than dacron. Now then, if you are of the school that considers any white triangle to be a sail, then go dacron.