Valves in my Hybrid Amp

[Schmuck]

My Unico Amp has ECC82 valves as standard on the pre-amp stage.
I noticed that Mr. Valve only stocks the 12AU7EH and 5814WA.

Will it be a simple swop out, if I ever need to replace the ECC82's?
Is there something to gain by swopping it out with a more expensive valve?

Thanks,

 

[Waterhond]

 

[LAV]

 

[handsome]

 

[Bravick]

 

[Ampdog]