Actually the is a good chance it will be. Large power relays tend to have issues with their contacts oxidizing and losing their conductivity due to lack of sufficient current being switched and will fail to conduct the tiny current rather early.I bought what I did because: I will be running it off a dedicated 12vdc 1 amp wall wart, it's rugged, the relay can be easily swapped out by our client without touching wiring, it was free next day shipping on Amazon. It won't be less reliable, will it?
Also they're frigging loud plus personally if I bought a product from you and saw such a setup as this with a huge relay running off a separate 12 volt source when a tiny 5 volt one that could have easily been powered by the units own 5 volt source was cobbled onto the system all just to switch a logic level signal I would never buy from you again just from the simple fact it shows you clearly don't know what you are working with and thusly likely know as little about everything else in the system.
Would you deal with a mechanic who put a tractor tire on your car because it 'fit the rim and he thought he got a great deal on shipping' even though he was told multiple times by multiple people how to do it the right way plus could have gotten the right tire for all around less had he done it?