Diameters I provided are butt ends of the stem, so smallest trees having a 8-10" butt up to a 24" give or take - sometimes bigger.
Hadn't seen the Eltec video of the GP, that one is new to me. Didn't get to see any of the Eltecs floating around in NZ, just spent the winter down there working in the bush. Plebeian, where abouts are you stomping around? I assume North Island.
The crew I was with ran the Southstars, one felling head and then a 630 processor. Some features I liked, other things were a toss up. I think I prefer the Pierce design in theory over the Southstar, but application is the real tell all. Mainly saw positioning and two sets of grab arms versus the standard two; more of a grapple versus a processor. Keto is floating around in my head too, but would be a processor only.
If the buncher ain't running, nobody is gonna make money in my neck of the woods. Processor is too slow to keep production up. We're also generally not allowed to delimb outside of the landing, or it is practice not too. Slash piles are burnt afterwards and need to be in a single spot. So as nice as it would be to fall and limb in the same spot, it's a no go.
I'm a fan of the Madill loaders, real simple design and great to work on - the new ones look even better with the Volvo motors. Great swing power and pretty stable if you're on decent ground. LOUD machines though, not unbearable, but not great... A 2850 would be a bit overkill size wise for me, but could be doable if one came up for the right price. The 3800 and new 3000/ 4000 would be way too much machine.