Clearly, you must do what you feel comfortable with. My point was not at all about a nas as backup (though I do use RAID which gives some robustness though a true backup is wise as well - stored off-site in case of fire or theft).

My point is that there is no requirement to update QNAP firmware. Just leave it alone on 4.2.0 and, in my experience, everything works fine. Meridian specify that you should disable automatic updating.

Actually, although I have no experience with an MC200, from having repaired a fellow Hiker's TwinStore, which is based on a Windows x86 motherboard, if the MC200 is similar I would be rather more concerned about the MC200 motherboard failing and becoming hard/expensive (through Meridian)/not possible to repair. At least a QNAP is cheap enough to just buy another. In fact, because I like the QNAP as a nas, but I don't use it for general nas duties, restricting it to Sooloos, I am going to buy a second QNAP (another TS-253A) to use as a general nas - including for keeping an on site backup of my music files. I will still be usefully in pocket compared with buying just one MC200 and I will have more functionality (such as almost instantaneous hardware substitution if I do get a failure).

Be careful about relying too heavily on things under the control of Meridian. With hardware you typically pay rather handsomely for repairs and in some cases they no longer repair things (which is why, purely as a hobby, I like to do it).

Cinema/Music: Trinnov Altitude32 8-16,218,Cloud 4 channel, Marantz UD5007,DSP5200SE(2+C),DSP3300(4),DSW(2),271,MShort Ceilings,AppleTV 4K
TV: Marantz SR7013 Wharfedale Diamond 9x4+Celestion(C)
Music: Roon,i7NUC8gen,QNAP TS253A, Sony Scala, MS200, Garrard DDQ650,Wharfedale Diamond 12.3
Kitchen: AD88 (bluetooth via i80).