Subwoofer to match my B&W 601s2,CC6s2 and DM600i

Plan on purchasing a new sub in the next few days to replace a worn out athena sub that came with the micra 6. I want to spend less than $500 so the svs pb1000 is on the list but im not sure if I should go ported or sealed. Yamaha new NS-SW300 Subwoofer specks and price make it very attractive but I have not found any reviews on said sub but the price online is $170 less so if it performs I should be able to double up in a few months.
Room is rectangleish 13*40*13*40 with a attached kitchen which takes up roughly half the space, and 10 foot ceilings.
Any suggestions ?
Flatsmaster, you may have already made your purchase. I haven't been on Audiogon for a while. Since your loudspeakers are B&W, then keep it simple and don't get overwhelmed with the plethora of subwoofers on the market. Stick with B&W. That's what I have done and they work very well together. I actualy have two in my system for improved and more balanced room loading. Your room is large and going with two subs placed apart from each orther would be the way to go. The only catch is that you're spend more than $500.00 for both new and possibly even preowned. But in the long term, it'll be well worth it.
I can't say enough about the SVS non-ported 1000. Great return policy, warranty, and craftsmanship. I bought two primarily for 2-channel music, but even at 1/5 volume they give me all the depth I need. $949 for the pair and free shipping on a 45 day return.