Bruce, I think that it is amazing that these Miller Bobcats are so powerful and so inexpensive new (such as Bobcat 250). Miller dealers on eBay want $3,000 with free shipping, for a new one. Is there some "gotcha" that we should be aware of? I am seriously considering selling my Onan DJE (6 kW) and getting this bobcat instead (9 kW). This way, I would get more generator power, better package, and ability to make money once in a while.
As has been said, these are much better bought as "A portable or truck mounted welder that has a backup generator as a bonus" rather than "a good long-run backup generator that welds as a bonus". The
3-phase output is a bonus if the field work you need to do is testing out 3-phase installations for rotation and hi-pot faults before Edison fires up the panel for real.
I wouldn't plan on running it as a prime mover for any great length of time. The generator sections might last for decades, but the 3600 RPM gasoline engines are only going to be good for maybe 500 (worst case) to 2500 hours (MAX) between overhauls.
Unbolt the engine, throw it out, get another, bolt it in - unless you want to go through all the trouble of boring and sleeving the block, finding oversized pistons and bearings, getting the crank turned and polished, etc...
They do make larger units that are Diesel powered with a 4-pole generator section running at a much saner 1800 RPM, but you will pay the same healthy diesel premium up front to get the much longer engine life on the back end.
I'm looking at one of these because they're small and light enough to either "toss" (with a crane) into my work truck or hitch up a small trailer, on the rare occasions I need to do my own field welding.
If I had a need for long term off-grid power I'd call for a properly soundproofed rental and let it chug along all day, all night, at 1800 RPM.
(This is Hollywood, they have gennys for rent so well insulated you could sleep next to it and never hear a thing. Just the low whoosh of the warm cooling air (mixed with the exhaust) coming out the top hatch. Air both in and out goes through labyrinth sonic traps, and they run double mufflers and a resonator before the exhaust goes into the exit trap.)