MartinLogan Dynamo 500 or SVS PB10-NSD?

[horror4life245]

Currently, I have an Energy XL-S8 and it isn't bad, but I prefer a sub that's a bit more overwhelming, however, I may use both so I'll have a 5.2 system. I just got back from Magnolia Audio and was recommended two subs. I heard the MartinLogan Dynamo 500 and it sounded pretty damn good. I didn't hear the SVS since that's not held by them. However, I was told that these two subs are quite alike and both will sound great. I want to make sure I pick the better choice.
Which of these two would you guys prefer?
I want something LOUD that will shake my bed and can HANDLE it...I don't want something that will blow from having it loud.
This would be hooked up to a Denon 1910, by the way.
Please post pros and cons for each subwoofer so I can hear some things about each.
Please let me know asap, since my birthday is coming up and this will be my gift.