I am wondering. I am a clix player and some of the items only come in one inch. How will this effect my figures. Will they not fit in some places or are they pretty close all around. All feedback is appreciated.

Clix dials are not actually 1.5" they're a bit bigger than 1.25" So if you use them on 1" grids they won't fit quite right. But they would likely still be usable, except in small rooms or when many figures are touching each other.

Alternatively you could work on some kitbash conversion of the sets. Or use the floors tiles from a set that does have 1.5", although some walls might need to be adjusted too.

Which set are you looking at? I've done some kitbashing of old set walls to 1.5", but I personally just use floors from the new sets. Or even build right on the clix map.

Just to add to the above; while the grid size is smaller on 1" sets, the props and wall heights are still in scale with clix based figures.

The set I am lokking at is the undercrypt.

I think you will have some space issues with that one. Especially in the hall way.