The point that ka3jjz (and many others) make with respect to LNAs is make sure you have the best antenna setup that you can manage before considering getting an LNA - it's not always going to the best solution or addition to a configuration in all situations. Sure, it's great to be able to have stronger signals, but if you have a crappy antenna setup that's inefficient for the particular type of transmissions that you're hoping to monitor, adding an LNA into such a situation isn't going to really help much.
It would be like having a crappy car stereo system (head unit + speakers) and then throwing in a huge 500 watt power amplifier thinking "this is gonna make it sound better" - all you're going to end up doing is having a more powerful system that makes the crappy audio louder than it was before: "Boy, that distortion is crystal clear now that I've put that amp in!"