Rob,
Have a look at the Pentax PCF WPII series.
I have 2 pairs of the older PCF WP series, the 8 x 40's and the 16 x 60's. They have 20mm of eye-relief, are fully multicoated, Bak 4 prisms, waterproof, fogroof and nitrogen filled. The 16 x 60 size is not available in the new series and I don't know why because they are superb. I have also used the 10x50's and 12x50's and they are very good. I think the 12x50's give a slightly better EOF performance than the 10x50's, albeit the TFOV is slightly smaller and they are both very good for binoculars at this price level. I have no problems hand holding my 16x60's for short periods and the smaller binos are fine in this regard. Here is a
review on Cloudy Nights where Ed Zarenski compared the Nikon Action Extremes to several Binoculars including the Pentax 10x50 PCF WP.
$500 is really in no mans land, its more money than you need to spend to get a good pair of binos and its not close to enough money to get the best.
A pair of the Pentax PCF WP II's in 12x50 will cost you about $270 from Centre. Net and spending up to $500 does not gain you a lot. The binoculars that will cost you $400 to $500 don't offer much, if anything over these and some are inferior. To get a noticeable performance increase you really need to spend over $1,000 and look at the premium products from the Japanese or German makers. Most of those premium products are closer to $2k than $1k. Some examples of the high end products are the Nikon 10x42 SE ($1,200) and my favourites, Leica Ultravid, Swarovski, Steiner, Fujinon's, Zeiss Victory's etc and the Canon IS binoculars.
CS-John B