Yes, definitely you will get a better deal going with a home made solution here.
Buuuut, there is an important point to highlight: The probability of synology fucking your data up is much lower than the average selfhoster. Unless you already know almost perfectly pros, cons, and how to solve problems without a data loss, you are not better than the average.
As an example, I went with a synology box even if I consider myself better than the average because the data in my nas is extremely (but really extremely) important to me and my wife. And the price was a reasonable fine in order to keep that data safe.
So, evaluate yourself : if. The data is really important and you are not a really good sysadmin then go with a professional solution. If not then go in DIY solution and learn in the process.
Just my two cents
I would recommend an LDAP sever for user Auth.
There you can create/authenticate user with a central repo in a machine independent fashion. Also having the possibility to allow /egate specific services from the central database is a big plus.
It seems difficult at the very beginning but it quickly pays off. Give it a try