I haven't really noticed an usually p2p throttling. Downloads seem unaffected and upload throttling seems sporadic (they must turn it on when congestion issues develop). I don't think Shaw has every used download throttling. Slow downloads are usually a result of the upload throttling (torrent/p2p protocols usually send more bandwidth to the people who can upload faster, which spreads the file quicker. If your upload sucks, the tracker isn't going to prioritize traffic to you).
As for the ASUS RT-N16. I quite like the router. I have a modified version of TomatoUSB firmware on it. The only downside is that it doesn't do 5ghz. Everything now runs on 2.4ghz. Wi-Fi, wireless keyboards/mice, microwaves etc... There's so much interference in my apartment from my stuff and my neighbors stuff. I ended up reducing the router to single band and finding one channel that seems to have low interference. I don't get the 300mbps advertised from wireless N, but I get a big chunk of the 150mbps from single band Wireless N. I have my PC, XBOX, and Mediabox hardwired to the router, so at least my devices that really need the speed have it