Yes, they are aerator pumps. I have been using these pumps to replace pumps in my boat, and I friends who have been using them too.. My experience with the 205fm is that I have been using this as a replacement pump since the late 90's on all my boats, and I have never had one burn out.
Most pump companies will say that aerator pumps are not as good as bilge pumps, but I have found that the parts in a Rule 205fm aerator pump are virtually identical to the parts in Rule's 27sm auto bilge pump(except for the auto bilge electronics).
If you cannot find the 205fm cheap, just send me an email, and I'll hook you up..
Bullet Lines email@example.com www.bulletlines.com