yep tried them. better than the chinese or russian stock, better focus, more articulate, and balanced but ultimately undynamic and boring. keep in mind a 5751 lowers the gain slightly and will in general cause some of the "bloat" to shrink. slight musicality taken away for better focus.
there are very dynamic 5751's, like the triple mica sylvania's, which i've tried and sound wonderful, but these will cost an arm and leg.
however, my fav in the jolida is the mazda chrome plate 12ax7. has great focus and musicality altogether, very dynamic too with good frequency extension on both ends.
