I assume you have a 30 amp 120 volt system. They both provide essential protection.
The cheap one does not protect against low line voltage. Low line voltage occurs often enough to be of concern if you are running large motors like air conditioning. It can cause over heating.
Frequency protection is not protected in the cheap one. In the US and Canada, frequency errors are rare to non-existent. Sometimes generators may not be configured for 60 cycles. It causes overheating in motors and transformers.
Outlets miss-wired for 240 volts instead of 120 volts by electrician's mistake appear to not be protected and have been reported, but again this is also rare. It will destroy electrical and electronic equipment in your TT.
I wish you good luck and happy trails ahead