Actually, the sector limit on JKEdit is quite low. I imported my 450-some sector level into JKEdit from JED to do some lighting (which is the ONLY thing, imho, that JKEdit has on JED), and JKEdit told me I couldn't add any more sectors. This may seem quite high to beginning editors, but it's quite annoying later on.
Plus, look at what reasonably good levels JKEdit has created compared to what JED has. JKEdit: Jedi's High School; JED: Centrifuge, Fusion CTF, the Massassi Level Packs, Drazen Isle, Riot!, and so on. JKEDit is user friendly, but is a lot harder to use once you get into the architecture that the better JED created levels have. Yes, both programms get really boxy, and unorigional levels released by them, but the difference between JKEdit and JED is that JED releases levels of MUCH better quality, where JKEdit doesn't really get past those lower quality levels. JED may be more difficult to begin with, but in the end, it's worth it.