I have a Cannondale Synapse Carbon and I love the fit. It is a 47 cm. Somehow I have not had any toe overlap issues on the tiny thing. The reach is very comfortable for me. Was the Cannondale a WSD?
Carbon will be easier to compromise, but I don't think it is going to be a problem with kids. My DH rides an aluminum Cannondale because if you wreck racing, the carbon would be easier to damage. We couldn't gamble with that at the price of bikes! You said you want to do group rides and leisure, carbon should be more comfortable the aluminum for that.
Your shop should understand that you have to ride what fits. Sure they want you to buy a bike, but the one I use is always friendly when people bring in other bikes. You are spending money there if you use them for service and accessories.
BTW- My second choice was a Ruby, so you can't go wrong with that!
Amanda
2011 Specialized Epic Comp 29er | Specialized Phenom | "Marie Laveau"
2007 Cannondale Synapse Carbon Road | Selle Italia Lady Gel Flow | "Miranda"
You don't have to be great to get started, but you do have to get started to be great. -Lee J. Colan