That's my biggest concern. We live in a townhome now and outside consists of an uncovered patio. The RecTeq grill cover and Napoleon cover are doing great.Still kicking myself for not grabbing one at the end of last year when they were on clearance for like $199 I believe. My Blackstone was not that old at the time and was a gift but already rusting. Had a hard time justifying it but it is what it is. Good luck with your decision. I think unless they are kept indoors all will experience the environment at some point.
I know I'll use the flap top more often, but even at that, on rainy days, which we've had a lot of this year, I'm concerned about the moisture getting in. I'll need to do a good job keeping it oiled & protected.
It seems the difference with people's results with Blackstone really depend if it's kept indoors vs. outdoors. The biggest complaint I see doesn't have to do with the cooktop, it appears it's the construction and quality of components used to construct the frame.