Invisiwire costs a little bit less, but there are reasons for this - a couple of undesirables.
First, it is not as thin as DeCorp flat wire. You were comparing prices of DeCorp DeWire 18AWG and Invisiwire, so let's compare thickness.
0.031 - Invisiwire says it is 1/32 of an inch
0.004 - 18AWG DeCorp flat speaker wire
Invisiwire is nearly 8 times as thick, so you have to consider that in concealment. It's going to install thicker on the wall.
Invisiwire has self-adhesive backing vs. DeCorp flat wire which does not (uses spray adhesive). The advantage here is for DeCorp, and I will tell you why I think this.
With self-adhesive backing it seems like your installation must go in one solid line with no bends. Flat Wire is designed to go places easily and put the speakers where you want them. A lot of times you may want to go from horizontal to vertical or vice versa.
With DeCorp wire you can make an angle, crease it down, and continue the install. This is not possible with self adhesive backing, because if you turn it at an angle, the adhesive is now facing out into the room!
Anyway, we've heard from inmypjs, who did install DeCorp, and I have used it as well for my 5.1. I would like to know if anyone has experience with this Invisiwire and if my thoughts on its cons are accurate. Also, what did you end up going with, Frostea?
~ Cheers ~