When I mentioned importing the zone files I meant by using the ZoneRunner GUI utility to manage the BIND configuration (importing/adding A, CNAME, MX, NS, etc). So long as you stay within that realm and don't edit BIND by hand, it should be supportable. I believe that editing BIND directly is what Deb is referring to as a custom BIND config. 40 zones shouldn't be a problem, either, I just don't think F5 recommends GTM taking over the full DNS load of thousands of zones that some customers have.
Denny
Altostratus
