You don't need boosters unless you have a very large layout and running 10 or more locos at the same time, the Ecos puts out 8 amps which is more than enough to cover most layouts. Also have a look at the Roco Z21 system, it does nearly everything the Ecos does for half the price, its a simple system to use and programming a loco is very easy, if your not keen on the smartphone app you can plug in most throttles into it.
I got mine from here http://www.scograil.co.uk/roco-10820--z21-digital-control-system-2365-p.asp
Its the cheapest that I can find as Gaugemaster are the agents in the UK and they sell it for £360!