Got a Phasor340 in the garage ( and a lifetime supply of black colourstix as well) and would not recommend it as a PCB coat, even though the wax will be a near perfect resist. The issue is the silicone oil that is used as a release agent on the drum, which will also coat the paper and the board, and which is also a near perfect resist as well. As well the wax prints are very easy to smear, and tended to do that just from handling.
Would recommend an older HP laserjet though, and a non genuine T shirt transfer toner cartridge, as these do print a very nice black.
Funny enough took the CF280 cartridge in to have it refilled, as it has been running with the "toner very low" warning on it for the last 2 weeks. 4600 pages printed though, while the OEM cartridge ( with the same average density of print as well) barely makes 2000 pages before fading, and shows low at 1500 pages. funny that, the refill is better all round, better black, better life and better price. Just had to buy 12 for the 1 year warranty period, so had plenty of refill blanks after that.