Owning one I can say from my point of view they are over rated especially in stock form, the saws suffer from a poor exhaust system, the plugged up factory muffler.
Once properly opened up, they perform to a more acceptable level. For the majority of people on here that want one, they have do realization that in small wood up to 30" that there is NO advantage over a 440/460/372/7900 etc, other than the Tim "the toolman" Taylor advantage of saying I got the biggest, baddest chainsaw in the neighborhood. They are fuel hogs, they are heavier than most want to pack all day. They are a niche saw for the true professional. I don't claim to be one of those, just a firewood hack. The only time ours see's use is when it truly is needed in the big white oaks and black jacks that exceed 30". The rest of the time the 361/044 or 460 can handle the job. I'm to the point were I would have a good woods ported 440 or 460 that will cut with any stock 660 and prolly out perform one and not have to deal with the fat bottomed pig.
Don't get me wrong, it is a fantastic saw, extremely well built, built for the professional logger. It's not the light saber that all the owners of 290 and 310 and 390's think it is. There simply is no advantage to you get to the big wood and for the average guy they are plain overkill. Most are sold because the customer has no limit on the pocket book or has an extreme case of cad and just wants the biggest and baddest, it's not about need but the want.
Although you won't get anyone on here to admit it, I'll bet you there have been several that have bought them that have been disappointed.
Most people would be so much better off buying a 441 or 460/372/7900 as they will do just about anything that the average guy needs to be doing.
I'll bet my new 460 will see ten times the use that my 660 does.