Glad to hear you are looking into Solstice Power. While Solstice can tend to cut through certain strings, if you aren't a frequent string breaker I would imagine it would easily reach the 2-4 week mark you are looking for, especially in thicker gauges.
What is your current set up string, gauge, tension?
Evolution might be the solution
to your durability issue (if you end up having one with Solstice), as we designed that string with the purpose of being able to with stand the sharp edges of Solstice, durability is no longer and issue in hybrid formats, it's soft elastic properties and silicone base coating, add a nice boost of comfort and feel. I could also see you using a thinner gauge if Evolution 17, instead of a 16 multi.
Flash, will give you more durability than you can expect out of Solstice Power. With a more durable string, one of the biggest characteristics you want is long lasting playability. No point in having a more durable string that dies immediately as you're just going to want to cut it out and start over again. Flash is a soft, livelier, co-poly that specializes in long lasting playability, it is our most durable string in our product line. We've seen players using it as a main and or cross depending on preference, with Solstice Power as well. It's also priced reasonably at $9.95 a set. The only downside to Flash over Solstice Power is that it won't have that extra bite and massive spin that Solstice Power is known for.
Flash is currently being play tested by TW.