CM600 or SB6141 with the NightHawk x8

First off thank you in advance for any and all information and insight to this post.

I am currently doing some network installation and configuration for a client here in the Minneapolis area. I want to be able to provide him the best service possible in regards to what cable modem would be the best match for his NightHawk x8. Currently he has done research and selected the SB 6141 and the CM600. I am sure I don't have to list the 2 MFG. I have always been a fan of the SB's and have used them with great success and no issues. I am not biased to the SB's. I have read through the reviews and posts on other sights about the CM600 andf feel that the CM600 is by far the best match for the NightHawk x8 on a network line provided by Comcast. Basically it makes the SB6141 look like a smartcar racing a exotic sportscar. I am just wondering if anyone has used either of the 2 modems in conjunction with the NightHawk x8. We are going to be doing some testing with each tomorrow, but if there is overwhelming evidence that would help us skip that it would greatly benefit the client and allow us to move onto other parts of the project.

Any and all information is welcomed and very much appreciated.

Thanks