Sal,
I got the set and haven't even listened to it yet, but think of it this way: if you buy the set and you really like it, you've made a great purchase and you're a happy man. If you buy the set and it's not your cup of tea, hold onto it for a few months and sell it on Ebay for a nice profit, then use the $ to buy stuff that IS your cup of tea. It's a win-win situation.
Viewed another way, if you DON'T buy it, it will sell out soon, never to return, and you may find yourself on Ebay trying to snag one set at a higher price.
My decision to buy the TKM set came about the exact same way as your thought process. I bought 'All Music'(That damn Nessa and his quality product ), and it struck me, and I had nothing else by Marsh and no Tristano, so I went for it.