Does changing tuning affect soound?

[tomsturges]

I'm thinking about dropping all the strings on my 6-string acoustic down a tone (apart from the top two which i'll only drop a semi-tone so my guitar is in fourths). This won't affect how 'in-tune' the guitar sounds too much will it?

And also it's not possible to damage the guitar by having the strings too loose, meaning there's less tension on the neck is it?

thanks!

tom