If your G150 job goes it will be difficult to get another I'd think. It's not popular over in the eastern hemisphere. Partly due to the fact it is a political pain in the proverbial if you want to go near the middle east. From job security a Hawker rating is much better.
There are quite a few G150's around in Europe now. Even the Russians like them. It's a damned good aircraft. You can't compare a 1900 to a G150...
As far as the "political pain" tosh about operating one in the Middle East.... Have you ever operated one in the region? We do. No issues either. We are based in the region and have operated to Lebanon, Jordan, Yemen, Congo, Sudan, Egypt, Qatar (involving Saudi overflight) Dubai, Turkey, Uganda etc etc. infact, I know of two G200's based in Dubai, kind of puts that idea out of the window...
Yes, a Hawker rating may stand him in better stead if his job goes, but that's not on offer, is it? As far as aircraft go, the Hawker is a POS compared to the G150. (Faster, further, higher, newer design, baggage hold etc etc)
Edit: The G150 has a Gulfstream data plate only - no IAI.