This is just a follow-up to my previous post on this topic.
I've continued to monitor this and it is working fine. I bumped my uplink speed to 400 Kbps for an extra 50 Kbps.
Recently I've been doing some big uploads to Youtube. The data is going across my LAN from a PC to the router and then across the WAN from the router to the Internet.
Here's what my link speeds looked like during this upload: