The 5992 differs from the 6V6 in that it takes more heater current (0.6amps, vs. 0.45 amps). This is within the capability of the Moreplay power transformer, but the series heater resistors may need to be adjusted.
The virtues are a very sturdy structure, a long and reliable life, and tight tolerance of the specifications - it's a very classy tube! The sturdy structure probably provides much reduced microphonics.
However, the Moreplay is already designed to operate very conservatively, which gives the 6V6's a much longer expected life than usual, and the the Moreplay is also designed to have much lower microphonic noise than the usual designs. So I would not expect much if any change in the sound, nor would I expect the extended lifetime to be of much significance.
In other words, it's real virtues are not sonic, they are engineering and construction virtues. They are also rare and expensive - currently offered at $120 each, on the site I checked (one of the more affordable ones).
