Interface throughput using SNMP / MIBs

There is no other (in reality) that will produce what you want. If you think about it, ay time you get a reading of 'rate' it has to be averaged over some period of time. That period could be anything. 1 second, 5 seconds, 60 seconds, 5 minutes. BigIP would have to keep lots of different values and calculate them (Think of the CPU time wasted) on the off chance someone would query them.

It's much better to support 1 stat (incrementing counter) and let you poll it and calculate the average over the interval.