I have owned both the Morningstar and Whisper. I still have the Morningstar and I don't see it going anywhere.
My Whisper was 64" 55@28 bamboo cores
My Morningstar is 68" 56@28 red elm cores.
The Nm whisper was a very nice bow. Steve's craftsmanships is amazing and his bows are very well built. I liked the 64" and that draw was smooth. I have a personal preference to elm over boo, or almost any core over bamboo go be honest so that was a negative with the bow. I can "feel" something in bamboo cored bows that I don't like and after 20 something bows having boo cores I prefer not to have them. I also am not a fan of the glass over riser look on the Whisper and most other reversed handled bows. I always wanted to see one like theMorningstar. And the most important part for me is the grip and the grip on the whisper was too small for me. The six NM I had we're all too small, that's not a bad thing just all personal preference.
The Morningstsr is a great bow. It's no secret here but I like my Berrys. I seem to have found the "perfect" bows for me. The Morningstar has an unfair advantage because its red elm cored (my favorite core). James craftsmanship is great his design is smooth, stable and zero Handshock. The straight grip on James bow is just phenomenal. The way it's made is hard to describe, but it just melts into the hand. Also, I love the look of how he does the reverse handle. Glass stops at the end of the ramps, and the riser maintains that classic American longbow look instead of the swoopy look of the Whisper and other reverse handles I have seen.
Bottom line is both are fantastic bows made by fantastic bowers. You asked for the opinion of those who have shot both, there's mine. Good luck on whatever new bow you decide on.