Effectiveness of old cast iron Vs modern radiators?

[d000hg]

Our Victorian house was renovated probably 15-20 years ago and has modern double radiators. In both our two front rooms we have long, low radiators... So long they obstruct virtually the whole of the only unbroken wall (due to doors, chimney breasts and windows in the other 3)

To me these modern radiators are ugly as well as space inefficient and I'm thinking to replace them with something narrower, possibly old style cast iron.

I've no idea if these put out as much heat or have problems I should know about... Any tips?

 

[big-all]

the more mass the greater the time delay between heat transfer
in other words if your radiator has twice the water content and 4 times the material you have to heat all the extra mass before getting the full heat out
then when you decide its hot enough you have more stored heat/energy being released

 

[Doggit]

You can buy modern radiators that look old fashioned, and they'll give you an output rating, but an old one (as big-all says) is an unknown quantity, and will require more water to heat it, as well as taking much longer to then out put the heat. Not even sure if you could fit a TRV to one, or how well they'd work.

Edit: sorry, forgot to add the link for some vintage looking rads
http://www.castironradiators4u.co.u...sS-HxSzC7h1z--24hX2WarITq_XilNlRoCM6cQAvD_BwE

 

[d000hg]

I'm not sure I cared if it is actually vintage or not... Sounds like an old fashioned replica is better, not to mention an original one could be in discussing condition?