I have an old house with six inch burnham cast iron baseboard on it. I recently had one split due to a possible freeze up. I was using a wood stove at the time. In the morning when the fire died it was cold, I turned the thermostat up, about 5 minutes later...BAM! Baseboard radiator had a six inch horizontal split. Is this consistant with a freeze or old age?

As the baseboard in the house is quite old and the valves/connections too. There have been some leaks here and there. I don't suspect this will get better with time. I am considering replacing all this with slant fin 30. My heating guy thinks I'm making a big mistake.

I'd appreciate some pro's and cons.