Brian,
I have 11 Shrews, and three of them (all three being Classic Hunters) have foam cores, with two of those foam core bows also having carbon backing. I like bamboo core bows, and all my bamboo core Shrews are very nice bows. But the foam core Shrews feel and shoot better in my opinion. My latest Classic Hunter has foam/carbon/uni-weft limbs and to me is easily the best feeling and shooting Shrew I own. Each individual has his own preferences, and what feels better to me might not feel good to you. The foam core bows, especially those with carbon backing, seem to have a somewhat more noticable, higher-pitched sound when shot than a bamboo core bow, but that sound is effectively reduced by string silencers to the point that it is fairly comparable to a bamboo core bow with silencers. That difference in sound in the foam/carbon limbs versus the bamboo limbs is not significant to me, but some people have commented that it bothers them. I am more concerned about the effect of the sound on game. Out of three shots I have made at game with my foam/carbon Shrews, I have hit all three animals (deer) and killed two of them. The two deer I shot at Solana Ranch were really jumpy, but in general none of the three deer I shot with the foam/carbon bows seemed to react any differently to the sound of those bows than to bamboo and other bows I have.
I agree with JC about the Morrison foam/carbon limbs being superior to the bamboo limbs. Bob Morrison says the same thing. I have 7 Morrison bows and some extra sets of limbs, so I have as much experience with comparing those limbs as I do with the Shrews. If you don't like the Morrison foam/carbon limbs, then you will want to try the Shrew foam/carbon limbs before you buy them because there is a definite similarity. That is understandable, because Bob Morrison has been a very valuable resource to Gregg Coffey in developing the Shrew foam core limbs.
Allan