Hi Frank,
There are two tables in the MIB that may give you what you're looking for.
I'm looking at the EXOS 15.5 MIB and I see a table called
code:extremePortEgressRateLimitEntry
It starts at OID
code:.1.3.6.1.4.1.1916.1.4.9
You should be able to query
code:.1.3.6.1.4.1.1916.1.4.9.1.2.1004
(that's port number 4+1000) to see the
code:extremePortEgressRateLimitValue
as an integer. It's not working for me on my test switch right now, but it's got a minimal configuration and some beta code loaded.