should I change my stocks and shares ISA allocation for my existing savings

or will the sell-down and re-buy be more costly than just leaving it?

"just a quick one" etc

On the original question, I try to keep most funds @ 7.5% and individual shareholdings @ 2.5% rebalancing every 6 months or so or if something goes particularly nuts. Am just getting rid of most UK stuff at the moment as don't see anything improving here for a long time.