First I'd like to congratulate for the hard work on this comment system, the best around for Joomla for sure. Now for the suggestion, well I was messing around the code and could start doing it, but just by watching what I'd have to discover how some stuff works in the code (I'm a joomla novice), I certainly won't have the time to accomplish it.
As simple as it appears, ordering by parents total votes descending is a good feature that would require just an SQL change and minor code in tree list sorting.
What I've been thinking is a weight system for this component for sorting the comments. Worthy comments goes to top, useless comments go to bottom.
How to measure it is the greatest trick, what would make a post worth? For starters, the obvious one is that registered users voting worth more than anonymous vote. So a field to estabilish the ratio for these two type of votes would be nice.
Besides that, the number of likes from child comments should have also an effect on how worthy is the comment, the weight should have a diminishing factor for each level, something that could be also customized by a field.
The total amount of childs should also enter in the factor, the more comments in a comment, the more it is obviously interesting for people who are browsing the article. Could be given a weight factor, also customized.
Other things could be considered, like amount of users posted in the same comment, time decay factor. integrating with a tag system for comments...
Well things can start to get really interesting for enterprise level. This is just a tought, I'm sure I won't be able to work now on a project like this, but I'd like to contribute if something like this started.
Hope this enlighten some people, today everyone is thinking about SEO but not UEO (user engine optimization, just tought about this now :p), browsing content faster for human eyes who doens't have the whole time to dig into 100+ comments for useful information.