That's basically it. Some agents want to hear more of the character's "voice" in the letter. Some prefer more of the author's. Others prefer hooks. Some hates hooks. Some want you to stalk them and want you to let them know you've at least read some of the stuff they've represented. Others don't. with the exception of hooks, where I believe the guy was saying "I hate bad or gimmicky hooks" (and further guessing, probably referring to things like log lines and rhetorical questions), none of them said "Show me character instead of author and I'll be pissed" either...they are talking about their personal hot-buttons, or things that are especially important to them. ideally you get all of them done well in a query, you don't cut voice completely because this is your "hook query". They're saying things they look for in particular, not exclusively.
One agent wrote on his blog, don't even bother to include the genre in the query letter. That gets sorted out later. If you are subbing to me, then I expect you know what genres I don't take. yet i doubt you'd be rejected for a 1-line "Peter MacPeter is an 81,000-page horror novel" because of the single word...it would just be ignored. However, since it is a single deletion and a clear request, you may as well remove it in his case--there's no point in sending out queries 15% faster if you increase your rejection rate by 20%....
Another said don't bother including word count. It's not that important (Although the consensus I get is that in a generic query letter, you should include a word count) you should...again, this seems unlikely to create a major issue, but again,a single, simple deletion
Basically, I feel like one can write a different query letter to cater to each agent they submit to. I mean, each query letter would probably still have same meats and bones of the story in it. It's just the little things (sometimes big) you have to change.