If you’re locked in for 15 years, you are very wise to get advice first.
I say: audition, audition, and audition. As others have mentioned, planar speakers are qualitatively different. I am a devoted planar man: dedicated sound room uses 4 Quad ESL’s and 2 Magneplanar woofer panels, home theatre uses 1 Quad ESL (centre) and 8 Magneplanar panels.
Both Quads and Magneplanars sing with Bryston amplification..With their 20 year (sic) warrantee, the used ones command a good price, but they are available and you could save money there. I would hold out for the SST series or newer.
Another place to save money is cables. I would buy cables for a maximum of $50 a pair to start with. Then, if you feel like upgrading cables, make any upgrade prove itself in your system before you commit to buy. Cables are by far the least bang for buck. IMO.
+1 for a dedicated power circuit or two.
Good luck !!!!