Good that you are starting to think about this.
First your most important question: Is this going to cause problems for your clients? I would say to roll it out slowly, ask for some that want to try it first, then let them use it for a few weeks and ask for another bunch. Then work with them. I would assume the answer is no, it will not cause problems, but here is the main thing to remember and this is IMPORTANT.
- Your clients equipment will have real on the net IP addresses, so firewall rules are important. Right now they are hiding behind NAT and do not pay much attention to security, because they are unreachable (kind of). After this change, they will be fully exposed if not protected from the firewall. It will be nice not to have to do NAT, but now your clients will have to block all outside traffic that is not established or related to an inside request and then let in services they wish to offer. Again, no NAT!!! The world is good again.
- Have you applied from ARIN for you IPv6 block? I would assume with that many clients a /32 or larger will be given. Just get your own to start with as it is worth it not to change them in the future and they hand them out willingly.
- Have the talk with your upstream providers about supplying you IPv6. Even if it is only one for now, that should be fine.
- I do not see any need for different equipment, but you might need to make some considerations on BGP for IPv6. I think you should have enough RAM to pull in full tables.
After you get all this started, I would suggest the Hurricane Electric courses to get yourself really good with IPv6. https://ipv6.he.net/certification/
and get a tunnel from them to start playing with in the mean time. (One thing to note, do not hand out HE IPv6 addresses to clients as Netflix blocks their address space).