The PI (power inserter) does not have to be within 15'. More likely, 150'. For example, my PI is in my living room, the SWM-8 is in the attic and ther is about an 70' run between the two.
Hmmmm just happened to have the paper work for the SWM-8 and the PI-29 at my desk this morning. No mention at all of a minimum distance (nor logically, can I think of a reason) between the two. The max distance is actually 200', irrespective of splitter use. I suppose too, it could be even farther away if the cable were high quality (you loose power due to cable resistance) or or was RG-11 instead of RG-6.
Also can the SWM support 8 new tuners and 3 legacy or just 8 total? M legacy port doesn't seem to be working.
As I understand it, the SWM-8 can support a total of 8 tuners. If you used 2 legacy ports, you'd have 6 SWM connections left.