Low term limits are a double edged sword. On the one hand, you want to get new blood in the system. On the other, you don't want to throw away all the experience the representative has accumulated. how effective do you think someone really is in the first 2-4 years?

A middle ground might be to make those the term limits, but require the representatives to not fill that position that 3rd or 4th term, but able to fill other positions and come back later. E.g.

  senate (6) -> senate (6) -> congress (2) -> congress (2) -> congress (2) -> senate (6)

or even

  senate (6) -> senate (6) -> congress (2) -> senate (6)

This would force representatives into other positions, while allowing them to capitalize on (and us to benefit from) their experience. We have a little of this already in advancement from congress to senate.