my home theater room is 19 feet by 17 feet i have decided to go with 4 m80's 2 front 2 rear, center vp 150. Not sure if i am insane if i used 2 ep 600 or will 2 ep350 suffice

If you can afford 2 EP600 then go for it, but 2 EP350s or EP500s would work very well. THe EP600 will play quite abit lower thanthe EP350s which is great for movies.

would i be able to have one ep600 standing and the other horazontil

That shouldn't be much of a problem.

i heard some feedback from axiom owners that the ep 350 v3 not alot of difference to ep600

QS8's are such nice surrounds that I would be tempted to go with those for rears. You could end up with a 7.2 setup quite easily.

if i used qs8 for rear iwould prob go for 2 ep 600

The differences are what I mentioned, the 600 plays lower and it is really most noteable during HT use, but for music not so much unless some pipe organ is in the realm of play. The other main difference is the 600 is able to play louder than the 350 but in your smaller room the loudness part isn't a problem dual 350s would be very good, just IMO dual 500s or 600s would be that much better. You can never have too much sub(allows for future larger rooms) but you can have too little sub for impact.

Smokey, either way you go it will be a kick butt system.

Are you talking "rears" or "side surrounds", there is a difference. Also, the 600 comes in both vertical and horizontal orientation, you have to order it that way.