OK, I've attempted to improve my breeder design. This new version takes 1177s to heat up, but most of the IHDs would end up melting from 1126s onwards. I'd solve this by putting it into neutral mode at 1100s to let the heat equalise, but that could get rather annoying (and dangerous...).
Heating config: http://www.talonfiremage.pwp.b…e=1j101010114010101001010, active config: http://www.talonfiremage.pwp.b…m=1j101010114010101001019. Note that this particular reactor is 6 chamber and is completely surrounded with water except for one space, which needs to be blocked off (I used reinforced glass) - this was so that I could put another coolant cell in to help a poor IHD out.
The advantage of this breeder is that it heats up faster than the one in the OP (if you absolutely must minimise the startup time), but it's going to need one phase of component shuffling during the warmup or you end up with a large hole where your reactor used to be.