I know it will be great for my local mountain which I rode last year about 2 or 3 times a week all summer (plan on doing the same), but not sure about whistler. I only go there a few times a year and do blue trails mostly but not sure if 140mm full suspension will do the job.
I've seen people with hardtails at whistler, but I want my arms to fall off on crank it up brake bumps. Will it do the job?
Yeah 140 mil bike will work just fine it might bottom out more than a DH bike but if you're riding just flow trails or even a little bit of Jank it will work just fine. Like you said there are hardtails out there that work to it just won't be as smooth.
There is a pretty big gap as far as 140mil bikes go. You can get an enduro race machine like a sentinel or a more party fun play bike like a Mach5 so I’d say that should be a factor aswell but you should be fine. Parts may break more frequently than on a DH bike but if you aren’t going a ton you will survive.
It depends on how much you weigh, and whether its air or coil? If when you sit down on it the fork fork sags by 15% go increase the psi so it will sag to about 8-10%, if its coil well just let the bike do its job. Either way it will work, and as tricyclerider said your part won't stay as pristine as they were before. If you are going to ride like Crab Apple hits I would be a little bit more concerned if you are riding coil that is too soft, if its air--again just increase the psi. And again it depends on whether your suspension is air or coil and how much you weigh in relation to how soft your suspension is.