I met archaos at a caching event when this cache had been set but not yet found. On realising that I recognised the title "Metamagical Themas" I decided I was in with a chance of being FTF. No such luck. I picked up the subtle hint in the title and progressed a long way towards the solution, but fell at the final hurdle or two. Now I've found the cache (after months of brain-wracking) I realise how close I'd come with my first approach.
Two things helped me to reach the final solution. One was a discovery about co-ordinates and notation which I hadn't known before. But the final enlightenment was achieved when I explained to someone how the answer I had wasn't anywhere near the right place. It was only as I specified what the solution ought to look like (roughly) that I realised how to turn my wrong answer into the right answer. At which point I gave myself a heft metaphorical kick for not having tried that before.
We chose a gloriously sunny winter day to head South and pick up this cache (plus several others nearby). Great cache and in retrospect a logical and obvious solution.