Carbon and foam are applications of two different materials, not necessarily done in conjunction with one another. While some builders and shooters have not seen the benefits of carbon because of the type of carbon or the way it was applied or some simply don't like it at all for whatever reason, I think foam as a core material should be judged on it's own merits. If you take the arguable and admittedly small improvements carbon may give to a limb out of the mix, it's awfully hard to not choose foam over bamboo for a core. I challenge you to shoot both, with just glass and no carbon, and see what you think. I'll bet you'll choose the foam for multiple reasons...I simply cannot find a single reason NOT to like it...and the price is typically within $10-$20 for that option. The carbon though, I won't make that bet. It definitely has aspects that not everyone likes or wants, and there is definitely a give and take with it's characteristics...unlike foam in my opinion. Carbon is not for everyone for sure, but I'm convinced foam is a superior core. I know the original poster asked for Shrew opinions initially, but I think the benefits of foam will be seen no matter what the design/model/maker of bow.
One last thing, after approximately 18-20 custom bows built to my specs from various bowyers, and another probably 30+ purchased used from various sources, I have learned the most valuable lesson I think anyone can learn about buying a custom bow. Do NOT buy ANY bow without shooting a representative example first. Carbon, foam, carbon/foam can be debated all day every day and still not amount to a pile of horse exhaust to the guy plunking down his hard earned money without shooting it for himself.
I'm no expert, but I did stay at a Holiday Inn once.