Hi, TDR.
I use the Prodigy 2 myself and I think it's excellent. It's more simple to use than a lot of other DCC systems (all the info you'll really need is printed on the back of the throttle!) and it provides 3.5 amps of power which is more than enough for 3 locos fitted with sound.
As a general rule of thumb a single, non-sound loco will use about .25 amps while a sound loco will pull about .50 to .60 amps. This is assuming you're using good quality, modern models with decent motors, some of the older ones can pull up to 1 amp. Either way, you have more than enough juice!