I had about 2000 hrs of King Air time, mostly BE-200, when I went to Initial Training for my first jet Type Rating, which was a G-IV. It was probably the hardest aviation training experience I ever had, but I did pass my Type Rating ride. The biggest factors for me that made it difficult were that I had no previous jet time and no “crew” time/experience - all of my flying (including my turbo-prop flying) had been as a Single Pilot PIC - and that the Gulfstreams are fairly complex aircraft (systems), compared to a lot of other business jets. I got all the study material for the G-IV months ahead of time, and studied it diligently before going to my Initial Training Class… it was still hard, there’s only so much you can get out of a book! I took four extra sim sessions (above the normal “allottment”) before taking my Type Ride, because I did not feel comfortable up until that point (though my Instructors kept saying “you’re ready” even before that). The “turning point” in my training was when I stopped trying to do every thing by myself and learned to “use” the co-pilot effectively. I mention all this just as sort of support for my contention that, in retrospect, a “simpler” jet is probably better for someone’s first jet Type Rating… but that doesn’t mean you can’t do it - I did. (I know nothing about Astras, no idea how complex they are.)
The other factors you might want to consider are: (1) Which one pays more? And (2) “Bigger airplane” = “Bigger Suitcase”… i.e. in a lot of operations, you will be away from home longer on the bigger airplanes than the smaller airplanes (which have less range).