@Phil *******
There are some caveats to using that border. Leaving Thailand that way is always fine. No issue.
Coming back in, if you're the driver of a vehicle (car or motorcycle), it's generally alright, as you'll get stamped in outside. Immigration outside (for drivers of vehicles) and the hall upstairs are two different things.
Apparently, according to some Google reviews, there is a 1000 Baht VIP option. I'm not sure whether paying this means guaranteed entry or not. All I can say is, do NOT enter through Aranyaprathet (Poipet is the name of the city on the Cambodian side and they don't have nearly the same reputation for refusal of entry, though it depends on your nationality, as the Thai side does) IF you do not have a visa.
Ideally, if you have a choice, choose a different border to re-enter Thailand at.
However, in my experience, Aranyaprathet has worked for me BUT that's because I ALWAYS drive my own vehicle into the country (I don't do buses or other forms of public transportation) and due to this, I can avoid the tough upstairs immigration queue with the strict immigration officials.
I also have my own policy, where I don't take foreigners with me through that border, due to how strict it is and the high chance of refusal of entry. Either I go alone or with Thai nationals (family members or friends).