I have been operating/managing the G150 for over the past 12 months, approx 500 hrs.
Our normal mission includes 3-4 pax, avg 2.5 hrs stage length, all domestic, runways >5000'.
We operate at Max Cruise FL390 to FL410 at TAS 460. Fuel burns: #2000 1st hr, 1500# 2nd hr, 1400# 3rd, 1300#, thereafter. When we are crossing the country, east to west, we will fly a constant Mach at .75 - .76 (430 TAS). LRC in the books is something like .69 - .79 in the mid FL300's.
The systems are very straight forward (see smartcockpit.com for the books). All DC electrical system, 2 hyd systems (main and aux), conventional flight controls (ailerons hyd assisted), deice on wings is via boot (works well, does not pick up much ice). The fuel system is interesting, as it holds 10300# pound of fuel in essentially 4 tanks. All passive (no xfer valves or pumps needs to maintain cg)
The Proline 21 is superb. We do not have the IRU option. Dual File servers makes it paperless and overlay weather is option (XM or universal).
Easy to hand fly and Land.
The items that are concerning:
-aft CG. We can go east to west across the country with about 9700# to 10000#'s of fuel at Take off(burn is about 8300 - 8500). However, if you must utilize all 10,300 of fuel or pax have alot of bags, a very thorough w & b is needed. Moving pax or ballast may be needed
-baggage door is small and in most cases a step ladder is needed. Our pax travel with duffel bags, therefore it is not an issue to us. If ski's or golf clubs are the norm, it is a major pita
- the flap/slat system is an issue fleetwide. We have not had a failure (yet) in the g150. I've experience multiple failures in the G100 and astra.
-Brakes are expensive, expect only 250 landings or so.
PM me if you have further questions.