The Nonsuch is a freestanding rig so there is no backstay to limit the roach of the sail. I've seen a few with Strong Track and full batten mains. Neither is better or worse for a beginner sailor. When buying a boat, the main thing to be focused on is condition and how well the maintenance has been done. I'd invest a bit extra in a boat that has been extensively updated. I'd find a broker who is familiar with the Nonsuch line that can advise you.
If you haven't sailed much, I'd suggest starting with the smallest and tippiest boat you're comfortable in. That's the best way to learn how to sail. A Laser is a great boat to learn how to sail a cat rig.