I'm wrapping up my last cycle indoor right now until the fall. I'm running 3k in a 6x13 room. I'm seriously considering building 3 huge sip beds. A guy I follow on freemygreenpdx has a pretty rocking No til SIP going. I've got 2 kids and work a lot of hours so anything I can do to make my inputs smaller without sacrificing quality or yield, is something I'm willing to try.
By fall you should have more data from this board.
Hyroot,
SomeGuy, (those threads cover years, and I didn't find the first mentions of SIPs, so the links are a little random... but poke around, lots of good info there) and
Thorhax off the top of my head, are all running DIY SIPs, and are sharing their successes and issues so hopefully a consensus will form in regards to the best and easiest methods by the time you are ready to put one together.
My indoor is approaching the end of week six, but one of my plants looks like it may be a 10+/- week flower, so I might have a ways to go before I pull my SIPs apart and look inside. Practical issues will come to light, like seeing how much clean up there is and how well the different designs lend themselves to being cleaned, if they are slimy... etc. And of course, I can't wait to see what the root growth is like.