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I've done some wide-area multipoint wireless links using amplifiers. The antenna was mounted at the end of about 240' of LMR600, 200' up a tower. I needed something to drive the coax - even with LMR 600, the cable loss was around 10 dB. I ended up mounting the amplifier on the tower at about 75' height.

Anyway - if I remember correctly, the amps we used (YDI, I think) actually worked bi-directionally. It had 1 or 2 Watts of output power towards the antenna, and something like 12 dB gain towards the AP. Without this signal boost, the link budget would not have worked out.

The problem with amplifying the received signal is that you are also amplifying the received noise/interference, so if your SNR was bad to begin with, you would just get a larger noisy signal with the same SNR.

My philosophy is not to use amps unless absolutely necessary because of these obvious issues as well as reiability/single point of failure concerns. I certainly don't want to climb a tower - even to the 75' level - to replace a malfunctioning amplifier (that's what contractors are for :))