Honestly, I'm surprised most tree crews aren't running Chinese clones. I'm sure they are not all this way, but the one's I've worked around are hard on equipment. If you're going to wear it out quick regardless of the brand, it makes sense to buy disposable. If he's buying them in 10 saw bulk orders, he's likely paying around $150 per saw. The Stihl/Husquvarna equivalent will cost 6x that. At that price, it's hard to justify spending any time working on them.k&n works fine on na engines at stopping dust and dirt, do not use them on forced induction engines...the vac to pressure pulse on na engines open and close the cotton gauze membrane trapping particulates in oil...forced induction lacks the pulse allowing debris through the expanded openings in the gauze. Any dirty filter traps more particulates but also restricts flow. Best chinese saw is probably the stihl ms170-ms180 assembled in usa Met a guy that ran a 4 guy tree service that had a small mountain of blue saw carcasses. He justified buying them in the multi packs direct from china and would run them until they broke...about 4-6 months then he threw them in the pile and opened another one from his pallet vs buying stihl at a cost of 4 of the blue version. He said they were under powered vs stihl but the end cost justified the method because every so often he would fix one using two others and often purchased new stihl carbs and clutch drum kits for them to keep on hand. I asked about bottom end longevity and he said some just come apart from crank or bearing failure but often it is the plastic tank/handle that fails from leakage at the seams, vents or they just crack. Most tree service groups around here run one 362 around large equipment or ms 17-180s for groundies...our local stihl dealers falsely condemn "low compression" on used out of warranty equipment in for repairs to sell more new units.
As far as being underpowered, that's a user issue IMHO. The Farmertec stuff is tuned a little sluggish when it arrives. If you're running a saw frequently, you need to be in the habit of tuning it from time to time. If your friend would open up a muffler for one and install it after the first few days, and re-tune it, most of his saws would run just as strong as their Stihl counterpart with the same muffler modifications.
I've been around a couple of MS180s. I don't are for them at all. I'd rather take the hit of an extra pound of weight and have an 026/MS260/MS261 or the Husquvarna equivalent. To me, the 170/180 series saws lend a lot of weight to the method of using 32" bars on 70cc saws for limbing.
I had a dealer pull the Low Compression crap with me a few years ago on my 036. Put a new spark plug in it and I'm still running it today. Compression is 150psi which is exactly what it was when I bought it used in 2010. It's been my primary felling and bucking saw ever since.