One myth is that a higher level tier makes your internet browsing faster. The truth is, unless you are hitting the speed cap on your current tier, you will not notice any difference in speed by stepping up to a higher tier. If you we're streaming a video from YouTube, you would average no more than 300 Kilobits per second according to Wikipedia. This means 4 devices could all be streaming video at the same time and only 1.2Mb would be needed. Keep in mind videos and music uses the most bandwidth where simple web surfing would only use a fraction of that. If you stream NetFlix, they recommend a 3Mbps connection for SD quality videos and 5Mbps for HD quality videos.
Your alarm system and cameras are generally under 100kbps.
Take a look at your internet providers bill and more than likely you are in a tier of 10, 15, or 25Mbps or higher. Dropping this down to 3-5 Mbps would save $10-$20 or more per month with hardly any noticeable difference whatsoever.