We have done Siblu for the last couple of years and they are great.
Kids clubs are better than Canvas or Keycamp in my opinion because they are dedicated owned by siblu sites without having a host of companines competing for space on the site. The sites have been clean and safe for kids. We have done Le Bois Dormant and it was great. They tried hard with the entertainment and employed local bands who delivered French songs in French to a mainly English(Brits and Irish) speaking audience and wondered why most people chatted and didn't listen.
Don't know about Brittany though since thats where we did Keycamp
beware of the terms and conditions.we booked in nowember with siblu and they called two nights ago and said our holiday at la carabasse no longer available and nothing we can do.If you read the contract you could actually be on your way to your holiday and they can cancel it and give you seventy five ponds compensation!!!!
We always go peak season. The only time I knew of problems was when a hurricane felled a forest and a child was killed by a falling tree so the whole site (Bicarosse) was closed - but that's understandable.
I've stayed on a Siblu site (Le Bopis Masson in St jean de Monts) and woudn't again. It was too 'Brits Abroad' and in yer face for me! the sister site across the road looked better tho - Le Bois Dormant. Siblu is Haven in the sunsg=hine basically! We usually go with canvas Life as you can still use tesco vouchers with them too!
Leslaki - Le Bois Masson was the worst/most crowded Siblu site we have been on. La Carabasse is much better laid out, more Green etc. Les Charmettes is fab & we have had no complaints with any other site. That part of the Vendee is very crowded & busy though.