I'm planning on buying a GTX 760 sometime soon, and I am considering SLI in 2-3 years.
Seeing as I use 1080p, and will for the foreseeable future, I was wondering if the 4GB would offer noticeable benefits over the 2GB once I SLI in a few years.
No, not at 1080p.
Don't try to predict hardware 2-3 years into the future.
Will you upgrade to an higher resolution after you go SLI? If not, stick to the 2Gb version.
Honestly, I dont think the 4Gb version is worth it. Two 760s 2Gb beats a single Titan in almost all games wich is pretty good.