I think the main problem is the time constraints set at Cons and how to decide games that don't finish in time. There's been a lot of talk and controversy over the topic and the fact that their decision has a huge impact on what types of books are competitive. Limited time availability (some of their tournaments have had less than an hour available per match) tends to favor aggressive books to begin with and the method they decide to base a timed victory off of can exacerbate that fact.
I think the current rule of deciding off of how much Life is remaining is a good one. It does show who was the closest to winning by the time the match ended and it doesn't require any additional record keeping at all. These are very big points in its favor. However, it doesn't necessarily reflect who had the advantage and was going to win, which a lot of people do not like.
It's kind of like if you take a photo of a race in the middle of it. If you had to award the prize money based on this photo, would you give it to the person currently in first place, or would you try to decide who would have won if they'd gone all the way to the finish? Trying to decide who would have won can be very complicated and controversial, but some people would consider it to be the more fair approach to take. It seems that Arcane Wonders may be favoring simply giving it to the person currently in first, however. Which is a lot easier to do and can be accomplished in a much less controversial way.
As long as the match is given enough time so that a control book can possibly turn things around and gain the lead, then I'm fine with the prize being given to whomever is currently in first when time is called. I don't really like messy and convoluted solutions for trying to figure out who would have won. Predicting the future is imperfect at best, while looking at who is currently ahead is very clear. 90 minutes sounds fair to me. I would even be okay with 75 minutes. However, when we go shorter than that, we begin to have a bit of hard feelings from control books. And sometimes they are forced to make matches shorter than that.