Originally Posted by
Dave Sheldrake
They aren't bad but they run hot...very....the actual output is the same as the EFR's but they tend to quote peak (YongLi), be aware, the first mirror is a circular polariser if you come to replace it inside the box and they aren't cheap ($400) the yongli is a folded resonator as well rather than a true dual cavity, that tends to cause a lot of heat at the semi/partial join (that's what usually blows up)
As yet the twin tube single body tubes haven't had a great run of success with the F220's that I know of going bang inside 50 hours (3 of them), the EFR is $4,200 inc 2 chillers and 2 power supplies.