I have a UAT environment set up on my client's infrastructure. We don't have Visual Studio installed on it and basically when client reports an error on custom developed features I am digging through ULS and trying to reproduce the issue on my development environment. If I am unable to reproduce the issue then I backup content database from UAT and restore it on my development environment. This is rather lengthy process since content DB is rather large and it takes some time to setup site collection admins, SQL logins etc. Exporting only a site is not an option since export takes forever to complete because we have very large lists.

What are the potential drawbacks of installing Visual Studio for debugging purposes on UAT environment?

The only drawback I can see right now is the inability of testing during debug sessions.