I found the Nucleus+ to be a step up from the dedicated tower I had running Roon sending a signal via USB. That said, I found the Nucleus got better when it ran as a server only.
I think that is the important point here. It is not bad as a server and player, it is better as a server alone. This is the case even with much more expensive devices.
The reason is that roon servers work best when very high powered as they are dealing with Roon DSPs and a very volatile internet along with other accessing flies etc.... Players, are best when mid-powered. Excess processing power tends to introduce noise in this stage.