Anyone here used EAR 519 monoblocks and have a opinion about them, one way or another?

They are the rackmount version of the 509s, originally made for pro studio use.
Same valves in a 19" rackmount format, front panel bias. Only difference is "519 amps have a separate screen supply which allows lower supply voltage with 600uf of capacitance" but I'm not sure what that means in practice, except perhaps the valves run cooler and less stressed..? Valves are supposed to last a long time in them. Sound is supposedly very neutral and transparent, not 'warm' and 'valvey'... some even say possibly too revealing/fatiguing for home listening.