mof1964 wrote: Any other reputable boilers out there?
There are lots of good boilers, more important is that you get a good installer, and hopefully there is a supply house in your area that stocks parts. Buderus makes great equipment. Biasi is very nice as well - there is a man in my local area that installs them and the folks running them seem to be very pleased. Slant Fin, Weil McLain, etc, I think they all work well if setup properly.
Don't forget about EFM and Axeman Anderson. They both make excellent steel boilers. You may want to consider contacting a local EFM dealer and seeing if they are interested in your 520. Perhaps they would be willing to remove it and give you some $ towards a new oil boiler. You could always install a second Chubby in the basement if the price of oil goes nuts. Keep in mind that if you get a new & efficient oil boiler, your wife will probably be even less excited about restarting the 520.
The Energy Kinetics System 2000 unit would probably be the most efficient out of all the units mentioned. They are very low mass, and the control purges the residual heat out of the boiler after every heat call. The up front cost may be more, but you would probably get it back in just a few years.