There are various reasons for this proposal, but the most prominent two are: 1) the possibility of starting on a world where rubber is a very remote resource. 2) Other mods which have items that can be /extracted/ to make rubber (but you can't build an extractor without rubber).
I thus propose creating a Basic Circuit which would be composed of uninsulated wire of some kind (I'd favor tin, but copper or gold might feel better for balance), a wool block, one redstone dust, and one Refined Iron.
This basic circuit would substitute directly for the Electronic Circuit in the Extractor.
It would also substitute for the wire in a Battery.
With the three above additional recipes and one additional /item/ the initial set of generator and extractor could be built without using rubber.
This would allow any sticky sap/resin to be extracted at the more efficient rate instead of cooking; or if using a mod like Redpower2 which adds other potential extraction sources (but not direct sources) of rubber a way of unlocking the alternate flow.