Any potential issues logging into an ARD session with a dedicated ARD user?
The protection of the ARD is in the fact that you can enable and disable users for this feature.

The brute force protection is that of the user account. You can set it up to lock after 5 failed attempts or what ever you please.

It is strongly advisable NOT to use an Admin account for this, but instead use a normal account to give access to the ARD, and using account switching or admin privilege escalation where and when you need it. Part of the reason being is that you can take over the session of any user currently logged in that way, without the user knowing. So IF you are worried about people breaking in to your account, that is the way to minimise the risk as far as possible.
(Best practice is that nobody is admin on a Mac apart from a dedicated account that can be used for privilege escalation instead) 

Hope this helps in your decision making process.

GJ