Yes, I do. Sometimes instead of using EQ, I change cabinets first to see if I can get closer to what I need. You can find some nice combinations.
If it sounds good, it is good.
Absolutely! The cab is perhaps the biggest influens of the tone of a rig.
I have a couple of cabs that I have saved from some great profiles, both commercial and free, that I often use when I find a profile that feels promising but lacks something extra.
If it sounds good, it is good.
This.
@MrGecko: The so-called cab driver feature does a very good estimation about what is amp portion and what's cab. If you like the results that's all that matters.
Absolutely! The cab is perhaps the biggest influens of the tone of a rig.
I have a couple of cabs that I have saved from some great profiles, both commercial and free, that I often use when I find a profile that feels promising but lacks something extra.
If it sounds good, it is good, right?
That's right. I got some awesome cabs that to my ears sound better than others in every situation. I use them with merged and studio profiles and always like them.
As always: Trust your ears! 
It's really all about that. If you like it, use it and you won't be wrong. There is no reference, no good, no awesome and no standard guitar tone. When the tone you like fits your needs i. E. plays well with your band's sound or plays well with your recordings, you've done everything right. 
The easiest way to test various cabs is to load up one of your favorit rigs and lock the AMP, EQ, STOMP and FX sections. I.e. let only the CAB section be unlocked.
Then preview the riggs via the Rig Manager that has the speakers you are interested in and only the CAB section is changed.
When You find something You like, go to the CAB section and save just the cab.
Some of the best cabs that are free IMHO are from Deadlight Studios, Sinmix and MentaL. But your taste might favour something else.
