The others have added a bit already so wont go into what you can/cant do. Will maybe just explain a little bit of the technology end of it, and how/why its different.
With Bell fibe, its IPTV. Bell satalite, your the same way as Rogers, but Fibe you do get the advantages as you listed.
With fibe, EVERYTHING goes through the PVR unit. Thats the reason there is a limit on the number of TVs. The PVR itself only has so many 'TUNERS' on it. When you are watching live TV on one of those remote units, its playing its live TV off the PVR box, streaming to the other box.
(that its wireless, etc... is an advantage of that the system is IP based.. much easier to do so)
Again as per above, since its doing all its tuners from the pvr box, this is what allows it to play/pause live TV.
WIth the rogers boxes, as each has its own dedicated line to it, each has its own seperate tuner in it. So nothing is taken up on the PVR box.
This actually allows one to actually record 8 things on the PVR itself, as well as watch live TV on all the 7 others. (vs on Fibe, where if you were watching live TV on all the other boxes, you would only be able to record one on the PVR)
Rogers, apparently soon, will be releaving an IPTV.. with new/different remote boxes.. wireless receivers, etc much more like bells. BUT then may fall into some of the same limitations.