Well I'm not an expert on the older Comp-Arfs but that flat spar deal on the 2.6 size birds created a real stink for Comp-Arf when people found out there was a "competition" version of the 300 in the fantasy scheme using a wing tube and it was about 4lbs. lighter than the rest.....

Then everything got changed to wing tubes instead of spars and they lost a lot of weight.

It's not a 260 for sure because I have one of those and it's got a wing tube and other changes you don't see on this model, basically it was the last addition to the 2.6 size models until the Edge 540 was released.

This is a Comp-Arf 2.6 size Extra 260: