Many years ago, at a time when most opponents were trying to win by filling 5 rhinos full of close combat oriented space marines, I played a list vaguely similar to the above. In a time when one could declare aspect warriors to be troops, I filled 2 wave serpents with banshee, 2 falcon with scorpion, and escorted them with a prism. I figured that if I was seeing all these mechanized marine armies, I could answer with mechanized Eldar. How better answer rhino rush than with serpent rush?
Except bright lance equipped wave serpents could kill rhinos, where the rhino rushers needed to get into power claw range to hurt a wave serpent. The highly mechanized rhino rushers were soon out of rhinos. THey then had a choice between huddling together, in which case my vehicles picked them apart from range, or they spread out, in which case I'd have three or four of my squads jump on one of theirs.
As I suspected, wave serpent rush could really clobber a pure rhino rush.
Another player issued me a challenge, after. An orc player. A Green Tide no vehicles overwhelm with numbers orc player. He lined up a tidal wave. I lined up in a nice balanced boring line of five Falcon hulls opposite him. 24 screaming inches of movement later, the balanced line turned into a refused flank, as my entire army squared off against half of his. I launched a perfect flanking attack. In those days, one could leap out of a vehicle and assault. Killed a lot of orks. It was pretty. It was an elegant example of Eldar speed and tactics confronting brute force.
Unfortunately, the attack barely made a dent in the numbers of the green tide. I just didn't have enough models with enough strength and toughness to take on that many orcs. No matter how elegantly 32 close combat models might attack 150 close combat models... I had a problem.
I have dreamed of playing highly mobile Eldar fast scouting forces on a basketball court sized playing surfaces with no limit on the number of turns. With the speed and range of a Prism, one might do some very interesting things.
On a six by four foot table with a six turn time limit, one can be forced into a more brutal sort of contest where one can't quickly disengage whenever one found one's self at a disadvantage.
So, yes, Eldar vehicles, while very capable, are also terribly expensive. If you try to mount you entire force aboard fast hulls, you might not find yourself with enough numbers against a hoard.
Wave Serpents and Prisms are also 12 12 10 unless they get moving fast. They are pretty fragile A mixed army with a goodly number of anti-tank weaponry would slow you down pretty quick. There are enough mechanized guard armies wandering around these days that you see quite a few armies that could demechanize your force reasonably quickly. I generally like holo fields and spirit stones so my falcons and prism last a bit.
My other thought is that the Avatar is the only slow model in your force. While the Avatar is much respected in Biel Tan. Still, you might want to consider one of the phoenix lords. With the above mix, it should likely be Asurmen, personification of the Dire Avengers.
I also like the Dire Avenger's bladestorm. 30 avengers hopping out of vehicles and unloading 3 shot each could be intense.
This style of list could be wild, but improved Eldar vehicles are expensive, base Eldar vehicles are fragile, and the size of the resultant list would be small. You might manage some cool stuff against the right opponent, but it won't be a general all purpose list.
Then again, general all purpose Eldar lists are hard.
