KEF207/2: tri-wiring and amp questions

I've had these KEFs for about a year, and they continue to be the finest speakers I've owned. They are built so that they can be bi or even tri-wired, and wondering if any owners out there have experimented, and if so with what results. I'm currently single wiring with Nordost Valkyjras and they sound great, but wondering if more is possible. ALso using a Dartzeel integrated (200wpc) to drive them, and wondering if more power would be worth giving up my fabulous Dartzeel. Thanks in advance.