TPG does not come close to Vocus's carrier grade international backbone.
Everything TPG does is on the cheap.
I think NBN will impact them the most. They use to have the best ADSL2+ deals for consumers going around, this will be impacted. I guess maybe they have foreseen this hence the investment into deploying their own fibre to compete against NBN...?
As for their commercial services. I am at a company now that recently moved off TPG's network to Vocus.
TPG are actually ditching their "old" network and are building products off AAPT's backhaul. So I expect anyone currently on that network to get a 2nd rate service as all their focus is on the new product. They won't want to spend money on a service that no new customers are going to be put on to, IMO of course.