patricej

i was using a 6600P when they first rolled out the 7700.
i heard nothing but good things about it, so my story is mine alone.
i offer absolutely no criticism of the 7700.

i decided to stick with the 6600P because the only advantage i could see [that was important to me] in the 7700 was 2 more inches of work space to the right.

i liked having the cone rack built into the 6600P vs. having to buy one separately to screw on.
i preferred the opaque extension table with the folding legs on the 6600P.
for me, the needle threader was easier to use and much more reliable on the 6600P vs. the 7700.

sooooo ... i was very happy to skip the upgrade.

that said ... i did fall in love with - and purchase - the Horizon 8900 almost as soon as it hit the market.
the accufeet are soooo much easier to change. just attach the adapter once, and the feet snap on and off.
the quarter-inch accufoot works fabulously on everything but tight curves. (i loved the quarter-inch accufoot on the 6600P for attaching binding, but didn't find it convenient for piecing.) now, i only use the "regular" quarter-inch foot on the 8900 for curved piecing.
i can finally do a little bit of free-motion quilting without finding eyelashes all over the back. the special bobbin case (costs extra) on the 6600P did make a significant difference, but i don't need it on the 8900.
(i did have to buy the cone rack separately for the 8900, but i got over that pretty quick. LOL)

my bet is that the 8200 would also be a dream to use.
it has fewer decorative stitches and a slower maximum speed than the 8900, but if it fits better into your budget, i expect you'd be happy with it.