Welcome motorhead9999.
You'll find we are in general a little pleased with our brand these days and for your landscape and astro, you really would be hard pressed to find a better performer than the K-1 paired with OEM and 3rd party glass choices. All of my fellow landscapers are nikon or canon shooters and sometimes i feel sorry for them missing out on some of our innovative features and quality. I'm not gonna let on of course, lol.
In general, where Pentax tends to trail slightly behind the competition is video, fast AF tracking, and flash sync speed; none of those metrics pertain to landscape and astrophotography, luckily. Besides that, the overall image quality including pixel shift functionality, weather and rugged build, astrotracer, tilt screens, sensor shifting(for shift lens effect), compatibility with ancient glass, and price point, all score a win in favor of Pentax.
Good luck shopping and feel free to ask plenty of questions!
---------- Post added 09-13-2017 at 08:44 PM ----------
Originally posted by motorhead9999 ...I've also been thinking about getting a crop sensor camera to complement my full frame. Preferably one with a higher shooting rate for sports or action/wildlife shots (and also possibly for close up star/moon shots, given that a nice zoom would get a bit of a bump with the crop factor). I'd imagine the suggestion would be "Get a crop camera in whatever system you decide to stick with". Which would be the best Pentax crop style camera to go with? ...
TIA!
I primarily use the 645Z for my landscape work and the APS-C K3II for wildlife, sports, event, long tele. I find it very capable and up until recently was using it exclusively for my astro work, until I actually tried the 645Z and find it able to hold it's own, despite the absence of GPS/astrotracing nor a fast wide glass option.