Thanks guys. It's a tough decision.
I don't think I'd want to put ds 1 up a class, the youngest class he is in the better, tho 4th sounds possibly difficult.
The thing about going to London, we could move to right by a grammar, then between now & then, ds would have to swot & cram & be under pressure for 11+ tests, just as it sounds like he will be in German system. Or we could not bother with grammar (even though they're def bright enough). But then so many comps are dodgy, it's such a lottery also in UK, see countless mn threads on the topic.
My plan is to put dc in german school for the next year (sep 2009). If it goes well, and we decide to stay then good, if it's terrible and they don't do well in school, we still have the UK option. It doesn't make sense to me to keep them in IS for the next year, decide then to stay, then move them into german system, and only then find it doesn't work.
Depressed to read so much bad stuff about it though. It is a concern.
Don't people say similar now about england system though? That too much pressure, constant testing, sats etc etc? is england system really so much better & why?