[Closed] Any suggestions for a HT frame upgrade?

My lad has grown out of his 16" mmmbop. We'll be selling it and swapping for another hardtail, but now he's ridden my Cotic guess what? He wants steel.

He's fifteen, he's not subtle. He's Clydesdale class and has SLX 2x9 drivetrain, Hope Tech M4s, and a 1 1/8th Thor 100-140 to go on it. Wheels are Pro II on DT 500's and I could do with not too much by way of extras to find, although I don't mind sorting seatposts etc.

So, what's out there? Dialled, Cotic, NS, Cove? Sanderson? He likes red trails and don't 'fraid de rocks. Speak to me. He has a hundred quid left over from Christmas, so that plus whatever the mmmbop frame will fetch.