The reason why holding Hills a certain way is so important is that it affects the bow alignment during the draw, which in turn affects 'hand shock'. The bow limbs, string and angle of the draw hand should all be lined up before shooting, with the eye over the arrow. Alignment starts with the hand on the grip and the better you set the grip the less chance of torquing the bow and so the less vibration at release, even with lighter arrows. Solid hand contact on the grip is an important and GOOD thing for Hills, as long as the contact allows the riser to stay controlled and in-line though the release. Gripping the bow the 'right' way changes a little from shooter to shooter because every person is physically different, but the alignment concept always applies. So, although 'handshock' is potentially greater for Hills because of their lower mass in the riser and higher mass in the limbs, it can be minimized by holding the bow the proper way.
Hills aren't for everyone but when (if) you finally find a grip angle that works for you they are about the 'most funnest' bow you can shoot. And I say that having owned (and still do own) many of the 'preferred' models both longbow and recurve (Widows, Morrisons, Pronghorns, Shrews/Griffins, 21st Century, Thunderhorn, lots more). Hills will either grow on you to the point of addiction or make you wish you stayed with that cute n' comfy little recurve that 'handshocks' something like a mouse fart on a marshmallow. Comfy yes, but also just a little boring. If you do try a Hill and decide you don't like it you can always sell it. But, you might want to keep it awhile and experiment with that grip style recommended by Hill shooters. Sometimes the 'Hey, that's fun!" lightbulb pops on later than sooner.