I don't know how much longboarding you've done, but if you've just had one go on an IMCO you're not really getting enough experience to really judge the way they sail. They are much more technical than a Go, which is (to many people) a lot of the fun and challenge.
Top speed of a good Raceboard in big breeze seems to be high 20s to low 30s, which is quite close to FW and fast enough for most people. The hybrids really struggle against longboards unless it's blowing 15-20; for example here the Techno 293 is rated about 2/3 the speed of a Raceboard around a course across the range of winds.
Of course, if you personally don't like the feel of a Raceboard, that's cool and let's hope you love your shorter board - but to give the longboards a fair go you may have to spend a bit longer on one and readjust your thinking and style.