I have bought a few. Fractal cab packs and redwires and own hammers. It can be a rabbit hole and it depends how much you like to tweak. If your a serial tweaker folders of 1000's of irs is probably heaven.
One the 1000's of irs I own I currently use 1 from cab pack 13 for pretty much everything. And if It doesn't work I use a stock ultra res cab. That said I like that 1 ir allot.
That said it all comes down to how much you like try different ir's. I'd rather use less and tweak the amp to get the sound
That is also one of the approaches I use myself. When I find an IR that I really like I don't feel like exploring a lot after that since the next day I might prefer something else and the next day... etc. and for that reason although my packs have the fast "Ace" folders you may or even should disagree with my choices if you really dig in since we don't all like the same things. Except when it's pizza = CP7 or hamburgers = CP13. :lol That is the approach essentially. Find an IR that you like the most and use that IR.
When you buy a real cabinet you don't change the mic positions every single time you start playing your amp. You'll find the positions that work and use them. Don't treat digital differently just because it's easier. It should make easy things even faster and easier.
If you're the type of guy who places mics with their eyes and is fine with it then I suggest using my Ace choices and not worry about the rest. They got through quite many ears and judging to get to that point that they're named Aces.
To make things more simple I usually have top 10 IRs which is the 10 first user IR slots and when ever I find an IR I really like it gets onto that list and those IRs are always the ones I try first when creating tones. Obviously the list keeps changing all the time but some IRs have stayed on that list for many many many months. Most of what I have in there right now are unreleased but the ones that I still have in there have stayed there through all kinds of tests. That includes: CP7 USA Trad SM57-MD421 01, CP8 ML Brit TV SM57-R121 F01, CP13 SM57-MD421 02, CP13 ML USA Bulb SM57-R121 03, ML Double Verb SM57-MD421 04... the rest I can't sadly talk about right now. Between 11-20 is where I have all the Ace Alloys from ML Class-A which will be out next. I'll most likely land on a few favorites and two of them will make it to my top 10 for sure.
But back on topic:
Is a Cab Pack purchase worth the money?
Hells yes if you ask me off or on the record. If you're that guy who was happy with a Behringer 4x12 cab with whatever speakers were in it miked with whatever mic you found you most likely don't care about IRs either. (Why did you get an Axe-Fx if you're that guy?
) But if you have a nice guitar or even a nice amp on top of that cab and say that you really care about your tone then I would like to inform you that a crappy guitar through a crappy amp going through an awesome guitar cab will sound better than what you're experiencing since out of these three the cabinet will affect your tone the most.
What I'm getting at here is: How much money have you spent on a pickup change? How much money have you spent on a single pedal? How much money have you spent on something completely insignificant tonally but visually pleasing like a cool looking strap? Do you have two or more guitars that sound pretty much the same? How much do you spend on strings in a month? I don't feel like even proving my point. IRs are way cheaper and affect your tone so much more than any of the things I just mentioned.
So I guess the real question is "Are stock IRs enough?" right? I think it's all about how important your tone is to you. Once again if you've ever changed pickups on your guitar or f.ex. A/B'd different strings, drive pedals, amp heads or done something like that to
find your tone. Then my answer for you is
stock IRs are not enough. An IR affects your tone way more. That is not opinion, that is fact.
The reason there are IRs from existing Cab Packs as stock IRs is to give people samples to find which Cab Pack would suit them best.