Anything is possible with wireless. It kind of depends on any external interferences, hopefully none or very low. Then how it's all set up. I have enjoyed playing MW3 via wireless N and haven't had any issues other than the lag that comes from the XBL servers and other users. 25ft is a pretty good distance. Also building materials can impact signal as well. Being in same room for me it hasn't been an issue. I have gamed from 2 rooms away using my DIR-857 thats in the living room currently and me and xbox in the bed room which is about 15-20ft away and a room in between the xbox and router. I was gaming last sunday using this. Signal was good, however bars on MW3 fluctuated between 3 and 4 bars, 4 bars being full. This was with out the 4500 being online.
Wireless N in itself is very good for gaming. So is G. As an example, I have a 4500 buddy from OK that still uses G I believe on BF3 on his 360. His is set up for 2 360s on G and one wired, we all used to play MW2 and BF2. Worked well if he DSL ISP keep good service.
You really need to figure out if going wireless will be good for you. You have any other users that need wireless or online while your gaming? If your the only person gaming and online and no others needed wireless, then it might be good for gaming. Personally, wired is best for gaming and streaming. However in some cases, wireless works well if conditions permit and configurations are set well.
My configuration is as follows: ISP modem(SB 6180 in Office next room over from bedroom)>long wire to my host router<DIR-857(Living room) 15-20ft away from office and bedroom>Long wire back to Office where 24pt switch is>Wire to my DGL-4500 located in bed room next door to office which is set up in AP mode and set for 5Ghz single mode N sitting right above my 360. I have the flexibility of using wired or wireless connection off the 4500. I had everything wired before however testing various platforms and senarios, I need to have some flexibility. Normally I have the host router located in the office with the modem and switch and the xbox and or 4500 directly wired to the 857 and not the switch.
For you, you just need to figure out weather or not it's worth going wireless for gaming as I mentioned above if the conditions can be met, good and setup done well.
Any questions?