I can vouch for the husqvarna's , been using them for a lot of years , but they are the XP models with air inject , tip a bucket of sawdust over them and the cooling fan keeps it cool. all chainsaws need maintenance , regular cleans and especially the air filter , my models are , the baby saw is an XP 55 CC , the middle saw is an XP 72 cc and big bertha is the XP3120 120 cc . all the bars are modified for milling timber ,the 3120 has 60" bar and has not let me down cutting river red gum slabs, a metre wide , cant say much about the stills, all the blokes I knew, milling, used huskies, my vintage saws were old model oleomac's, both 82 cc , rebuilt once , had 2 of them but the fxxxn servo sold me super fuel that tasted like acetone years ago , and one seized and is good for spares ,the other began to slow so I stopped and saved it from seizure , my 4 stroke engine on my saw bench started puffin out white smoke , thought i bought diesel but looked at the docket, its was super, crap from one of those independent sellers , never use the low octane stuff, or ethanol, just 95 unleaded these days but always use husky 2 stroke oil , there is a dolma laying around and all its good for is laughing at. it was a gift , some gift . those look alike chinese saws , good copies , a bloke bought one and had to replace o few bits the chin tensioner screw thread made friday, night poorly made , I have a few look alike engines, the fuel fitting on the tank snapped thought it was plastic but looks like a poor quality casting , the new one is a home made job by me. the donk is a honda lookalike motor a thornado , goes ok so far .