Good question - certainly, the 1/4" signal chain will be better for it but I suppose it depends on where you are? If it's a gig where there's still a DI need to front of house (either another house box or they use a pre-EQ DI from the amp) then I would say yes - the output from the 1/4" is near identical to the ear as the XLR - certainly in a gig environment.Is the Neptunium worth having just in a 1/4” signal chain? Or is the magic solely in the XLR out?
But if you're playing just the amp - either on it's own or miked, then I'd say you may be better with something more like a regular pre-amp, so you have more options to play with. Possibly something like the Slampegg, Elementary or Underground Accelerator?
(I suggest those three, but I've never played them - it's just what I would be thinking of doing).
Unless , of course, your amp has a value preamp - then you're already sorted.