That too - forecast says max VSP 800fpm - but flying for hours in IMC being constantly thrown about is incredibly tiring, even with an autopilot.
But would you be "constantly thrown about"? In my experience, you get above the boundary layer and it's smooth enough. I accept that terrain can change that.
Indeed, but unless you were lucky and hit a period when there was no-one else wanting to fly the TLA SID they'd be unlikely to accept someone climbing slowly at, what - 90 knots? - and clogging up the system.
Well, how do you normally depart southbound IFR from PH? Why would that be difficult today?