I had the same dilemma and the only reason I cut mine back was because the leaves were marked with dots and didn't look healthy. I probably wouldn't have done otherwise.

I've compromised and cut back half way because tender ones under glass always seem to do better if cut right back.

I cut the larger ones back to the ground, and left the stems of the shorter varieties intact (and shooting). It will be interesting to see the effects later in the year.

Thanks for the replies.
Looks like I'll be experimenting with cutting back.

wont you be too busy shooting spiders,tigers, slugs and snails ? id leave them myself .

Left it as it was. Had my best ever display. It ended up 6 foot tall, 6 foot diameter. Far too big. So now I've cut it back.
And yes, by cutting back I can see pests more easily making it easier to shoot them.

awesome you da man

I know, keep reading, you might learn something

ow I have learned something rest assured bud .

good lad.

I've just posted a picture on my fuschias which are still flowering away. They are in a very sheltered place so I won't cut them back until really necessary.

that's ok pa