Interesting that lots of people say they live in Grammar areas, but their kids are at Comps. If there are Grammars, there cannot be any true Comps because to be a Comp, you have to have access to the full range of ability, without any ability groups being creamed off....not possible when a Grammar is around. When there are few Grammars, which are superselective, the impact on a county, is often much smaller, because few from most areas go to Grammar, so there is less creaming off, but there is still some, so strictly speaking, the other schools are not true Comps.
It's great to hear from people whose kids go to the non selective school in a grammar area and are pleased with it. Too often though, the non selective options are not great, and bearing in mind that well over half of kids have to go to those, it leaves a system that isn't good.
The problem is that the school system generally isn't good or fair. If you are poor in a Comp area, the chances are that your catchment Comp isn't great and you are stuck. If you are clever and poor, at least in a Grammar area, you have a chance of a good school, if the non selective options are not good. And if you're not bright enough, but affluent in a Grammar area, you may find yourself stuck in a not so good school, whereas if you were in a Comp area, you'd probably live near a good Comp, so get into it. The problem is that the Comp system selects by location and affluence and the Grammar system by ability. A working and fair system would give a good education to everyone regardless of ability or affluence. Of course, the grammar system is made more unfair because of the huge correlation between affluence and having the means to get into grammar. Yes, some very bright children from deprived backgrounds do get in, but we know those figures are shockingly low. It tends to be the affluent families whose children get the preparation to give them the edge that get the places.
It's not fair. So back to the Q and to the OP, I would say, that you need to decide what will suit your children best. If they are bright and very likely to pass the 11+ then a Grammar area can be great. However, if they are borderline or weaker, and you have the means to move to a Comp area and live within catchment of a good school, it is a safer bet - in fact a great Comp tends to do as well for its bright kids as a Grammar anyway, so overall this seems the safest and best option. Many middle class parents love the idea of Grammars though and can't quite believe that any Comp can deliver similar results for bright children, and love the kudos of Grammar, so stick with it. Given the crap system which doesn't work for the less academic or for the more deprived, think you need to weigh up the odds for your particular children and find the best for them.....even more tricky if you have more than 1 and they are quite different!
Children in Comp areas definitely have a less stressful Year 5 and probably 6.