They both operate on the same principle--conduct the heat of the water through the cast iron into the air. You're trading aesthetics off. One issue is that you need a fairly long run of baseboard to give the equivalent heating "power" (i.e., amount of heat given off by a unit) to equal one of those decent sized old radiators. A heating guy can do the calcs, but when we did a renovation we mostly reused the old radiators in part because we needed a lot of wall if we wanted to switch to baseboard.

You are lucky to have nice hydronic heat in your home, congratulations. A heating contractor might better be able to help you pick out new heaters, but that is not a sure thing if you talk with a very experienced plumber in an area with lots of hydronic heat around. You might be able to re-use some of what you have if you can find replacement end caps since you might need two more. It depends on the design of the heaters. If you can, it might save you a lot of money if you want to match the other 7' length. With an open basement It should be relatively straight-forward meaning not too expensive, but I can not really say how much. I am not sure why you want to move it. The TV should work in front of the baseboard with no trouble. You might drive yourself nuts if you want to move your heaters to accommodate your furniture in every room ;-) What fuel fires your boiler? Who is going to be servicing your heating system?

I have a old home built around 1900, give or take a few years. I have a hot water heating system. Mine has the old steam Rads but were converted to hot water by changing the valves, and bleeders long before I owned it. you need to know what type of system yours is, hot water or steam? steam systems can be a one or two pipe system. hot water is two pipes. the two pipe steam and hot water systems use one to send out hot water or steam to the rads or baseboars and one for return. One pipe steam uses the same pipe to send the steam to the rads or baseboars then when it cools and condenses back to water it runs back to the boiler via the same pipe to be reheated. the two pipe is more efficent and if the system is steam you can convert to hot water with out major replumbing since it has a return. I have been told that hot water systems are less costly to run since you are only heating the water to 150 or 160 vs. 212 to create the steam. also check to see what kind of boiler you have and how the water is delivered. If there is a circulator thats a good sign the boiler is not super old like mine was when I bought my house. no curculator pump means its gravity system that relies on the heated water to rise natrually and fall back by the returns. I changed out my boiler last summer to a new forced hot water system, it heats the rooms much more evenly than before. the trouble spots for me were the radator valves, some of mine leaked when I refilled my system. I was able to tighten up the packing nuts and stop the leaks. my old system had a manual fill and the valve was stuck shut so I could not add water to completely fill the rads on my 3rd floor. That is now not a problem with the new boilers auto fill. If you have Rads you should purge air from the bleader valves at the begining of the heating season. you may not have any air in them but any air trapped in the rads will effect the heat output. check out Burnham's web site they make and sell boilers rads and baseboard for hydronic heating systems. that my help you inedtify what is in you home. Here is a link that might be useful: Burnham

If "ranch trim" is really short with just a radius edge, then it's what we have in our living room, hallway, and a couple bedrooms. It's maybe 2" tall. It looks much better to paint that trim the wall color, which then means paint anything on the wall the wall color. Also, I wouldn't worry about trying to keep them consistent from room to room. The goal would be to paint them -- in each room -- in whatever way would help to camouflage them best.