[The_bluester (Paul)]

There used to be a fairly substantial advanatge to Aussie Broadband, in that while they were well in the middle tire price wise they actually invested in enough capacity on the NBN side (the connection and the bandwidth to use it used to be essentially separate things cost wise) and proactively upgarded their backhaul links between NBN and themselves.

The current plans from NBN include a component of bandwith in the access charge which has brought the cut price providers up much closer, now only backhaul is a significant difference.

Typical peak speeds refers to what you can expect to realistically get during peak times (More or less evenings between about 5 and 10PM, basically "Peak" times being defined as when people get home and actually want to use it!) If you are on a 100/40 (100mbps downoad and 40 upload) plan you might see 95/38 or so in the middle of the day but only see 40/30 in peak times.

"Back end" capacity is generally gong to refer to your providers backhaul links. To get data out of the NBN in any specific area and into their own networks they have to connect to the NBN POI (Point Of Interconnect) for that area, that is the backhaul link and the cheaper providers tend to skimp on that backhaul capacity, just as they used to skimp on the CVC (NBN Bandwidth) before a chunk of it was included in the basic access charge.

TL;DR:

If you go with a cheap provider, you are more likely to end up with one that is skimping on backhaul capacity and more likely to see greater peak time congestion. I have no idea how the HFC version of the NBN is panning out for congestion within the NBN side of things, and that is a separate matter. I am on NBN fixed wireless and currently enjoying speeds that make out old 8KM long ADSL service look desirable (Think 1mbps in peak time) and that IS NBN's problem, which means I can look forward to months more of it.