I love my XP18CC, mine has the 70 on it. Not trying to steer you away from the 90, but consider the added weight of the 90 before you decide once and for all. My little 70 does pretty good. I've added a 6" setback jackplate and re-propped mine, improving just about every aspect of handling and performance, some aspects more significantly than others. The huge gain here was raising the motor almost 6" higher than the factory setup, that's a huge amount of draft when seen in context.
The 90 should have more low end torque, which would help when loaded. Top speed should be a few MPH better too. With the factory setup I'd expect to see about 40mph top end. And things would only get better with a jackplate and tuning, if you're so inclined.
As for the G3, I seriously considered it myself. The one feature that appealed to me is their forward mounted fuel tank. That would be much better than the rear mounted tank almost everyone else uses, especially with the heavier OB on the back. I went with Xpress because no dealer anywhere near me had the G3 1860 in stock at the time, nor could they get me one in a decent amount of time.
Also, the G3 is a true 1860 hull where the XP18CC is actually an 1856. The XP narrows a bit more at the bow which, in theory, helps it handle chop a bit better, but does so at the cost of a bit of deck space. Both are Mod-v hulls, obviously, so i doubt the ride difference is much in chop, if any. Not sure if the extra 4" of width at the stern helps any measurable amount with actual space in the boat, but in theory it would add some stability, though it hasn't been bad with my rig.
Not sure what trailer G3 uses, but I can tell you that Backtrack trailers are the downside of Xpress boats. At 6months I had one of their tires give up in a catastrophic way, and it tore the whole fender assembly off the side of my trailer. No help from Xpress other than to sell me the replacement parts for me to have welded back on. Before I could finish the 250mile trip home the other tire went out of round, and I was lucky enough to get it replaced before it failed. Their bias ply tires are junk. I've since replaced them with radials and no problems. Now, 4yrs later, I have found two welds on the trailer that are starting to crack, so there's another bit of money I'll have to spend on it. The lights they use are cheap, and failed within the first year, so mine now has LED's on it.
If I had it to do over, I might well go with the G3, but I wouldn't avoid the Xpress either. Mine has been a good boat so far, and is a fishing machine. Another to seriously consider is SeaArk too. They are built like tanks, but the price also reflects that. Honestly, my next rig will be a 2072, so that would force me to re-shop all manufacturers.
