I've said enough (or more than enough) about the 805. As for surrounds, they are not that critical, especially for movies (you will most likely set them for an 80hz crossover so the sub will do all the bass anyway). Now if you listen to a lot of audiophile-grade 5.1 music, they are more important. I only listen to music in 2 channel, so I am using very inexpensive Infinity 150s for surrounds with movies. They work great. Dipoles are very good for surrounds because of the diffusive soundfield they produce. Personally, I would put the money elsewhere.
Your center channel speaker is the most important speaker in your HT since it handles the majority of the sound and also, most importantly, vocals. If it is not well-matched to your Snell L/R speakers, things will shift in sound quality as they move across the screen. This will become irritating over time, trust me. Audyssey goes a long way toward integrating the speakers, so if you are close on the speaker types you will likely be okay. If the center channel speaker makes male voices sound boomy, creates sibilance on "s" sounds, or sounds lifeless and boring, this is a killer and Audyssey won't help. Spend your money on the center vs on surrounds.
Your center channel speaker is the most important speaker in your HT since it handles the majority of the sound and also, most importantly, vocals. If it is not well-matched to your Snell L/R speakers, things will shift in sound quality as they move across the screen. This will become irritating over time, trust me. Audyssey goes a long way toward integrating the speakers, so if you are close on the speaker types you will likely be okay. If the center channel speaker makes male voices sound boomy, creates sibilance on "s" sounds, or sounds lifeless and boring, this is a killer and Audyssey won't help. Spend your money on the center vs on surrounds.