My philosophy is "use your best judgement". I realize doing so much not involve "following the law"...but, if you're flying safe, away from people, then why should it matter? The govt has gotten WAY over zealous where drones are concerned. A few 'bad seeds' do some idiotic things, and then, all of a sudden, the govt wants to nail down every drone user. Just as with motorcycles, "it's the few who give the many a bad name".
I've installed external antenna on my TH, moved the 3rd antenna on my ST16 to the top (effectively converting it into an ST16+), and installed a hi-gain 4Hawks Raptor. With the stock configuration, you can only each 0.5-0.75 miles. However, with the mods I've done, I've flown over 3 miles (and, no, I haven't tested "max distance", so I can't answer that question, even if you asked)...but, in doing so, I wasn't anywhere near people, thus no 'danger'.
Personally, if you fly "safe", the govt shouldn't have any say in how, or how far, you fly. I believe that, depending on where you're flying, even the 400ft ceiling is ridiculous...if I'm not flying near people, I should be able to at least go somewhat higher...I don't think 1,000ft is 'unreasonable'...again, as long as you are in a COMPLETELY "safe" area. If you're anywhere close to people, then I agree work the 400ft ceiling.