Avoiding nute burn by swtiching soils ?

Just want some clarification on something. I've been using MG soil for my plants and even though i'm using bio bizz organics nutes i've managed to nute burn my plants. Could that be because of the soil ? as it's already treated with MG chemical plant food ?

If i switch to an organic soil like bio bizz all mix would be harder to nute burn them as it's all organic ?
I've had a few people say to me it's pretty hard to burn a plant with organic food, so i'm wondering if it's the soil that's the cause of all these problems.

Also if i use bio bizz all mix should i still mix perlite with it ? even though it says it already contains 30% perlite. And one last question which is better all mix or light mix ?

yes and no..all mix has feeding amounts that last up to 4 weeks!! so feeding is not needed thru the early stages... i use bio bizz and there hole range love it!

Does that mean yes - if i switch to organic soil it'll be harder to burn and
no - don't have to mix more perlite with it ?

Also how is all mix with seedlings ? i've heard it could possibly be a bit of over kill (nute wise) for a small plants