Since I discovered how hard it is to swim while holding on to a boat that wants to sink I'm a firm believer in having flotation added to kayaks...other than simply having "water tight" storage areas. I have zero experience with minicell foam, but I have used the blue styrofoam at the bow, stern, and bulkheads with very good results. I have installed it at the bow and stern with and without fiberglassing it in. I prefer with fiberglass. The bulkheads I have made up to 4" thick, cut to size, and fiberglassed completely around before installing with epoxy fillet and tape. They have worked fine so far. I suspect that I will never quit trying new things...so I keep an eye open for what other people are doing.