The 635 is supposed to be a real nice performer (better than most when it comes to running n with b/g).
You may want to hold off a bit longer (like me) until about end of the 1Q of this year as many new dual band routers are coming out.
Then again, you may be able to get the 635 for a bit cheaper due to this as well.
But, if you do get the 635, you should be happy as it is (arguably) the best one available now.
You should be happy with it.
It does not have a separate wireless/wired MAC address filter (at least with the last firmware version available) so if you use MAC address filters you will have to add both your wireless and wired MAC address's, but that is the only REAL gripe many people have with it.