I currently have a serious spidering infestation and I've tried several products that turned out to be crap. I only have 3 weeks left so is it worth trying something new? If so, what is recommended?
With only three weeks left in flower I'd be hesitant to be dumping anything on those plants. I'd look for something without any toxins in it. NukeEm is basically citric acid and works pretty well from what I've been told by a couple friends. Regardless of what you do at this point your buds are likely already contaminated with dead bugs and bug crap. I've used a vacuum with a screen on the end of the hose to suck up what I could. I don't spray anything on flowering plants.
You can also do a preventative spraying of neem weekly while in veg. I battled mites for years but haven't had them since I started doing preventative maintenance. I also don't go in other peoples grow rooms or bring in outside clones or other plants. I filter my air intakes and keep everything clean. No dead plant material, spilled soil, etc...
You might want to check out the "Bugs" forum as well.