I have tested and used the rca 20db inline amp and yes they give you about a 10% increase in strength and quality.Make sure u install them between the lnb and switch,not before or you'll blown or shorten your switch life expectancy. You should not need them if your dish is aimed correctly. but for long cable runs or cheap coax,use them by all means.
In-line signal booster is mainly for analog signals Waste of money Even for digital cable is becoming old tech Use RG-6 double shield or quad shield with snap and seal connectors for up to 175 feet yo'll be fine, take my word.