I like the idea, and have played on servers in 1.3 and 1.6 that had items take up multiple slots, could be a fun way to have more powerful items, but Lace is an essential item, powerful yes, but very much needed if you wish to survive so that should probably still take up 1 slot. By taking up 2 you can be certain none of the other multiple slot items will rarely be used since lets say you had an item that let you bullets light someone on fire or something, that would be cool, and could be powerful on the right races, but you would still be raped by the vagas, shadow hunter, etc.
I hit Brett right in the feels.