Depends on the tournament. If they say that Forge World units are allowed, then the Shadow Spectres and Wasp Walkers would be fine to use.
As for Vypers, my favorite way to run them is in a squad of 3 with dual Shuriken Cannons. They provide my anti-infantry and some anti-tank. I back them up with dual Bright Lance wielding War Walkers for serious anti-tank. The speed of both units coupled with target priority (there are a few Wave Serpents out there too) keeps them alive at least until turn 3 in most games for me. They have consistently made their points back each game as well. Vypers also can double as a decent anti-air unit.
To each their own for an Aspect list I suppose. I've always interpreted the Eldar fluff for Biel-Tan that they simply have more aspect warriors than the other craftworlds (Ulthwe more psykers/guardians, Saim-Hann more vehicles/jetbikes, Alaitoc more rangers, and Iyanden more dead guys) rather than there being no Guardians and psykers.
Honestly, the listed I posted above is the only list I ever play a fortification in. My other Eldar lists don't use it and are very mobile and hard hitting. But this is a foot list and has a couple static units that certainly benefit from having it. Also, with only the one unit of Spiders I find that in my meta I need the anti-air from the Quad-Gun to help with Heldrakes, Vendettas and the like.
I also agree that whatever list you decide to play, do it because you enjoy playing it and it fits how you envision Eldar (or any army for that matter) to function. After all, it is just a game