Yes you are right, in terms of detection and performance, Avast is better. And of course acquiring AVG, increases investments and helps to face competition with more resources available.The chances of failure that AVG may disappear is very minimal so far, because it brought already the trademark name and represented technology/equipment.
So of course Avast will still focus on their own product meanwhile AVG may lead for some enhancement.
But in such test, the circulation may remain same. Avast is better than AVG based on claimed independent test.
Which of course your goal is to increase the shares and you have already gained control on the possible changes on competition.