Update: On Wednesday, I picked up the sump upgrade kit for my E-260 and ran into a couple snags, but with RedSea's help in Houston got everything worked out. At first, the store I had order the sump upgrade kit from didn't want to include the plumbing, and tried to charge me an additional $90 for it, but with a call to Steve at RedSea in Houston, he got on the phone with the distributor and got it handled. Next, I got home excited to set it all up, and noticed there was not any return pump vinyl tubing, although the instructions say it was included. So I called Amanda at RedSea in Houston, and she got that sent out the same day and I received it yesterday. So fast forward to last night...
I was able to get the upgrade completed and running, and I'll share with you a few initial thoughts.
1) it operates pretty quietly and added over 10 gallons of water volume to the tank
2) the process of adding the plumbing was very messy (I drained as much water in the back as possible, but water continued to enter the back chamber and I didn't know it, I guess there is a small leak in the silicone between the baffles in the back wall, but not a big issue. So when I would unscrew the seals, there would be a ton of water rushing into the sump below and all around. It actually tripped my GFCI during the process).
3) the return plumbing outlet seems a little high, when tilted all the way down, you can hear the water flowing out of the pipe on top because it's coasting on the top of the water
4) it comes with the mesh filter socks, so I swapped with the felt to polish the water better.
Overall, I'm very glad I did the upgrade, but there are a couple small modifications I may need to make to ensure it runs as it should. I would highly recommend if you plan to do the sump upgrade, try to complete it before you start running the tank. Below are a few pics of what I installed.
This is at a higher water level than recommended and covers the return line, may use here