I would say that he either top Pete's 14 Slam wins (which is highly unlikely) or wins this years' Grand Slam. A career slam plus a calendar year Grand Slam...with 11 slam titles IMO would put him at about Pete's level.
Exactly. If Andre were to win one more FO and one more Wimby, then with a career double Slam there would definitely be "talk".
Most tennis observers, I think, can see that AA has a much deeper game-- he does more things "well" in tennis. The problem is the things Pete does "well", he does extremely well, including by far the most important skill in tennis: the serve.
Beyond that, Agassi's two biggest problems when his career is stacked against Pete is his lack of consistency and their head-to-head record, particularly in Grand Slams.
While knowledgeable tennis fans recognize that head-to-head is among the least important factors in determining which player is "better", Andre's lack of consistency relative to Pete, is hard to overlook.