can you hubstack or synergy cap an atmosphere… and is it worth the money to get them?
You might be able to put synergy caps on, but if you want to try hubstacks, find somebody near you that has something with hubstacks or just buy a PGM (plastic Grind Machine). It’s like $10 more, but you get a whole new yoyo. 
Or maybe a moderator could hubstack it.
If you’re looking to actually catch it during tricks then go for synergy caps. I don’t know if Synergy Caps fit the atmosphere so the best way to know is to contact André. He told me that Synergy Caps were no longer in production until they fix a little problem or something.
If you want stacks then check out the modification and look at the list of modders that might help you.
Hubstacks - no. Synergy caps yes, but it’s up to you as to whether or not they’re worth it. Personally, they’re not really any fun after the novelty wears off which is about a week’s timespan at best.
I hope you don’t mind me making changes to your sentence. 
There.
But really. Don’t go through all that modding just to get hubstacks on a yoyo. Like I said, honestly, they’re not fun after 10 mins. If you really want hubstacks go buy a pgm. If you want a hubstack like feel on your atmosphere, go for the synergy caps, but beaware that add alot of weight, and can totally change the feel of the yoyo all together.
My friends are addicted to hubstacks. They can’t get enough, like he bought an 888x for the hubstacks and same for his C13, and PGMv2. They do get boring after a week. I usually use them to make my combos smoother, like I would do a hand or finger grinds, and the pick up the yoyo with the hubstacks and whip the string on.
can synergy caps be taken off
Yes.
Oops, sorry. Typo. I meant a modder.