also, it's less important/less used than my laptop or phone, so that further makes the $600 upgrade a lower priority

Still, reading on an ipad is the best electronic reading experience imo. Kindle would beat it if you could display pdfs or math books reasonably. But an ipad beats the crap out of android for battery life; not necessarily screen-on time, but the silent drain when you leave it shut in your bag. When I leave my ipad in my backpack for a week, 1-2% battery is gone. My android tablet would drain in a week.