Is the size true to size or need to size up?Different people at various online Q&A are stating one thing or another.I wear Mens size 11 1/2 which would mean Lge but some people state XL.Which is correct? Don't want it TOO roomy or else it won't fit properly!Thanks!

Tech Specs:

Material:

Nylon 

Insulation:

700-fill Down 

Sole:

Rubber 

Weight:

[Pair, size 9] 11.6 oz (332g) 

Recommended Use:

Winter camping, tent-to-tent visits 

Manufacturer Warranty:

Lifetime 

Country of Origin:

China