Redex have allways produced a good quality range of products. TV's fifth gear had a bit about restoring performance on an old engine. They used a 2.8 VW Corrado dyno'd it then set about trying to restore the lost power. First thing they did was chuck in a bottle of Redex drove it for a week to let it work, dyno'd it and found it had gained an extra 5hp for the cost of £5.
In a two stroke it would probably clean the carb jets, my elyseo 125 i used it on when i opened up the carb it was silver inside all clean compared with the gun metal colour of the outside.
Sounds good to me it just a tad funni when idle after a longish trip so trying to rule out bits n bobs to find out why
Ok - but when you start it next day - does it run ok then? If so then sounding a tad funny idling after a longish trip can probably be ignored as a non-problem. It's easy to get a bit over-sensitive about an issue - but the majority of the vehicle industry works quite successfully on the basis of "run it until it breaks and then fix the broken bit". Anyhow - the balance of opinion above is that it will do no harm, and may or may not help. Let us know how it goes. Keep the black bits on the road and the shiny bits uppards.
Be brave, take a deep breath, and try a bit of Redex - it works out cheaper than using petrol from the expensive pump. If it smokes you'll know the answer and you don't have to use it again.