I have a Fender Princeton Reverb ’65 Reissue purchased about 5 years ago. I love the sound I get with it (although I use it for guitar only). There is one problem, which may or may not occur with a melodica: It rattles at certain frequencies! I think one of the mounts for one of the tubes does it. Actually, I had to tighten a few things on the amp as multiple things were rattling after a while. The aforementioned tube mount thing still rattles at moderate volumes though (like 4 and above) around Bb-C on the E and A strings on my guitars.
If you test this amp, I recommend listening for this rattle as it might affect your decision. TBH, it hasn’t really shown up in my recordings though!