This depends on multiple factors:
1. The Bars are just an icon and the treshholds differs - it's like on mobiles, where on device 1 you can easily have calls with 1 bar, while device 2 is not usable with 2-3 bars.
2. It depends on the quality of the chip/antennas - the surface chipset and antennas where claimed as "long range", so you could enter wifis other devices would not even recognize. IMHO the wifi in my rt is ok (despite the limited speed), but seems to have problems showing full bars even when the router is in the same room.
Example: While my girlfriends laptop showing 5 Bars (at -39dbi meassured with inssider at 2,4Ghz two rooms from the router), the surface shows 4 bars and between 2-4 bars on 5Ghz. The only time i'm getting 5 bars on 5Ghz is 0,5m (1.6 ft) away from the router. At the other moment is was able to use the network at university from another building with a 6-lane street and some big walls between me and the last access-point (yes it was not the most reliable connection)
As for the lack of a arm-version of inssider (and a lack of 5Ghz at the laptop), i'm not able to put those observations into some comparable figures.
3. The hick-ups you had could result out of the limited speed of the surface itself, the stream of the tv (apps like zatoo are relying on p2p and are known for such behavior) or your wifi-signal. My advice would be: Use Inssider and Ekahau Heatmapper to inspect your network and something like LanSpeed to measure your throughput. With those programms you can "easily" finetune parameters or the position of your router to gain some bandwith without having to buy a new router. Mitchellvii had already given some ideas.