what considerations for changing height of replacement radiator?

[jkn]

Hi all
    I'm looking at changing a radiator in a bedroom shortly and wondering about
my options re. sizing.

The current radiator is 900mm W x 600mm H, and is single panel, no convector. So
looking at some representative specs, let's say 550W output.

I would be replacing this with a single panel, single convector radiator. From
looking at the spec again, the same sized radiator gives around 50% greater
output - 900W.

I am wondering about fitting a 900mm W x 450mm H single panel, single convector,
which would then reduce the output again to 700W or so, similar to the original.

My reason for doing this would simply be 'neater appearance' of the smaller
radiator, but it wouldn't be a problem if the replacement was the same size as
the original. I am wondering if there is anything else (apart from power output)
that I should be considering here?

The radiator will be under a window and the CH is an olde school 'plan C', I
think. I would probably fit a TRV in any case. There is no need to heat the room
any better than currently...

Thanks for any advice.

    Cheers
    Jon N