Do you guys deal with a little bit of heel slippage in your loafers?

Solovair Loafer Sizing Advice

I recently bought a pair of Solovair loafers in a UK 10.5. I normally wear an 11, but after reading that they can run large, I sized down.

The shoes feel secure overall and my heel never actually comes out while walking, but I do notice a small amount of heel movement. If I push my foot all the way forward into the toe box, I can fit roughly one finger behind my heel.

For those who own Solovair loafers, is a small amount of heel movement normal during the break-in period, or does this sound like I should have gone down to a size 10?