Serif vs. sans-serif will always be a point of debate, although some studies have shown that there's no significant distinction in terms of readability, speed, etc. However, a majority of documents in the legal world, and patent world specifically, utilize serif fonts for a few different reasons.
First, it's just habit, Times New Roman (or Cambria) is the default in Word and most people don't bother to change it. Second, historically documents were all printed (and to a large extent still are), and serif fonts generally prevail in that medium.
However, I think that serif fonts (despite some studies) do force the reader to slow down somewhat as serif fonts generally command a more serious attitude than their sans serif counterparts. This is important in the patent law context since verdicts and invalidity arguments can hinge on the meaning of the words "or" or "and" within a claim. Also, bold and italic styles for serif fonts stand out more which allows for more emphasis when needed.
A couple of side notes, the PTO often uses Arial for correspondance and it is one of the most frustrating reading experiences ever when you have to read each word carefully. Also, SCOTUS requires the use of a Century-based font, which is probably one of the few things that is tough to argue is wrong.
Probably TL;DR given the subject, but it's the one part of practice that is heavily ignored.
My two cents: keep Georgia et al., increase the line-height to maybe