Hey Richard,
While Keyboard Maestro does a good job handling text-expansion macros, it does not provide as sophisticated a UI as TextExpander.
If you're managing that many expansions I recommend you stick with TextExpander. I use Typinator myself and have 48,330 text-expansions and counting.
On the other hand you may find that Keyboard Maestro is more than adequate for your text-expansion needs.
Search the forum for “TextExpander”, and you'll get 30+ hits. Amongst them are methods for extracting expansions from it. There is also some discussion covering when KM is a good replacement for a dedicated text-expansion utility.
Create some text-expansions in Keyboard Maestro and test them. Play with the differences between KM and TextExpander and then decide for yourself whether you still want to consolidate.
-Chris