@Tom D : I was going to do basically the same with my Defender and go down the M57 + auto, decent seats, an integrated aircon system that works etc.I had decided a while ago that I would buy a decent classic RR. My plan was to fit an M57 diesel, and an apple car play radio unit and a few other bits and bobs. Then the Grenadier came along and it had everything that I wanted and more.. then I saw the price of RR classics... Hence my Grenadier order.
I don't see the need for gren based RR. The RR was basically a comfy defender, and so is the grenadier.
But as you say the Grenadier has come along and giving me everything I was wanting and more.