they're great pumps. I've thought about changing out the ceramic shaft with a carbon fiber one. I'm pretty sure it would work if you could find the EXACT diameter.
I must agree with the others, they are great pumps. Much less heat releasing than Magdrives. But when you use the amount of Ca/Alk that I use they undergo calcerfication very quickly. To get them good again you need to clean the ceramic shaft, such that the impeller glides freely. Getting that shaft out is how I have broken them each time (one time I did drop the damn thing).
Russ PM me when you get them. I would like 4 if possible for the 1250 model.