Yes, they will not hold smaller diameter sheets or halyards. You will wind up buying ridiculously larger diameter cordage than you need which might have been fine back in the dinosaur days of stretchy double braded Dacron, but you can do much better. Pass on them. For some strange reason, Lewmar never made a retrofit kit to replace the self tailors.
Hmm... That's not my experience with them; my 55's will hold 3/8" dyneema cored line just fine, and the drums/jaws are huge. The biggest problem with these units is that the jaws are anodized aluminum; and on the wave grip the anodizing tends to wear off and then the aluminum corrodes. In addition on the inside of the grip rings where (they attach to the drum) the stainless bolts and drum tends to react galvanically with the aluminum grip rings. So you get corrosion in there and eventually the ring will fail if the corrosion is not prevented.
A stiff rotating drum on one of these units is usually a sign of sticking of the stripper support ring which is sandwiched between the jaws and must be properly lubricated and free of corrosion. the plastic components that keep the ring sliding above the aluminum are delicate so be careful when disassembling a dry/frozen unit (soak it in mineral spirits overnight if it won't easily come apart).