Those Propels should definitely be kicking butt on the Venoms. Did you form charge them? Have you run a few cycles through them? Give us a bit more information about what is going on. Maybe we can help you to get them to perform better.
If you form charged them and ran them through 3-5 cycles so far, then I would get in touch with Tenergy. Apparently their customer service is pretty decent and they will replace the packs, but don't do that until we find out some more information. NIMH need a few cycles to get going, so maybe you just haven't run them enough yet.