A couple things...
1. Beware that the DS do have a midrange thing going on that some may not like. Its unlike any other pup I've heard
2. One thing you might consider if money is still tight is the SX shortscale jazz bass with different pickups. I have one and have a set of DiMarzio Model Js in it. Sounds very good and full. The Model Js have pole pieces which are adjustable in terms of height so you can get every string perfect. If you bring the bass to a good luthier he should be able to set it up with low action. You might have to have the nut filed or replaced and I'd also think a fret dressing would be a good idea.
As to the Landing models I would email Jimmy. He is a great guy and very helpful. He will likely be able to answer questions better than anybody.
BTW, I put active EMGs in an SX ss P I really liked the tone. Very clear sounding. However, I've never been a fan of active basses and the hassle with batteries so I swapped it.
Good luck.
Thanks, I do like the SX as far as general build quality for the price (I seem to have gotten a good one neck/fret/body wise, the nut, tuners and bridge are another matter - adequate is about the best I'll say). The electronics really aren't up to snuff, and I don't want to invest a whole lot in it, though maybe a new pickup, nut and tuners would keep me happy for now without costing too much. No other inexpensive short scale has really enticed me into considering it, even a mid-priced Fender Mustang I tried didn't do anything for me.
I'm guessing the YouTube clips I listened to aren't giving me a totally accurate sampling of the Darkstar sound, since I didn't really hear the more pronounced midrange you mention. I have to find a DS-equipped bass with flats and give it a try first before I consider it.
Actives I don't think would bother me, I'm a knob-twiddler from way back, and as long as there's a way I could get a sound I like, I'd be fine with it. As far as asking Jimmy, I don't want to pester him until I can pay for what I order outright. I asked him questions last year, only to have to back out. I doubt he was a hundredth as disappointed as I was about not selling me a bass.