Bob & I have communicated via PM but thought I'd post the answer here for future reference by anyone else interested and searching.
I confirmed to Bob that the MS 34HTs are solid hull below waterline but cored above. I've been into mine in both areas and that was exactly what was found.
Lower hull was drilled for a new transducer and it was solid.
Upper hull I did a repair of an exterior gel coat crack by grinding into it and laying up several layers of cloth/resin to span the crack. I found coring in that area. Inside was reinforced to avoid a repeat.
Above is what I've read in reviews of MS boats and is typical of many brands / models.