I have / have used both. It's a pain in the ass to have the only range finder you have with you on your gun, let alone have a ballistic computer built in that will only give (or only "conveniently give") data if it's just ranged something. Then having to dial back to your zero between targets is dumb. So I see targets starting at like 400 and going to 1200, why would I not want to just range them all real quick while I'm scanning them? With a weapon mounted laser only, I have to have it dialed to zero, range 400, then bounce it back to 0 mils to range the next target. Even better, have your spotter feeding you distances while he scans for more targets, and you can dial or hold with no steps in between.
With thermals, yeah, having to point your gun everywhere to scan is also retarded and a pain in the ass. The good ol' boys I've shot with used a cheapish thermal scope on repeatable QD rings and just threw it on the rifle when they were all set to engage. With a little more budget, just keep a smaller scanning thermal around your neck while looking for hogs, and the weaponsight one on your rifle.
The above is why I said earlier that if you can have just one, it should not be on the rifle.