You know you can cycle the fork or shock to equalize just fine with the compressor or pump attached, right?I use the compressor to put 100psi in, then cycle past 30%. Then start pumping and every 50psi I pause and push it past 30%. Get to target pressure, remove pump, and cycle past 30%. Re-attach pump, hit target pressure + 2psi, remove pump, cycle past 30%. Should now be done.
As for owning an air compressor if you own a modern mtb....yeah. Unless you really enjoy being covered in bike industry lizard jizz while you do the crossfit dance of a floor pump for your entire cycling career, you should probably own some legitimate shop tools.