Virgin can vary depending on the area.
I work from home and to avoid the cost of going to the office when things arent good use two connections. So in your situation would get Infinity 2 and if I got close to 80 Meg would get a slower Virgin service as a back up, or if Infinity was down near the 30 Meg mark, but the faster Virgin as the primary.
If you have kids at home, the two connections is useful as it means you can let them use the one you dont use.
THOUGHT: Do you have to upload lots of data back? If yes the Infinity 2 has a much better upstream speed