Zerogee
Clencher's Bogleman

in regards to boosters: What constitutes a "big" layout?
Pretty big - not like Space is big, but quite big nonetheless (with apologies to the late great Douglas Adams!).....
Sorry, to be serious, I don't know of anyone in my area who has had to resort to a booster because of sheer size of layout or length of track - you'd be talking of hundreds of yards of track before you'd need one for that reason.
The more common need for a booster is if you have a central station with a relatively low power output (5 amps or under) and want to run quite a few trains at the same time. This can happen with central stations that were primarily designed for the smaller scales, where a booster might be necessary to bring them up to the sort of power output that G scale needs.
If you have a central station with enough output (like a 12amp Massoth setup), you don't have half a real-world mile of track and you don't want to run ten or more trains all at the same time, then really a booster shouldn't be necessary for most people.
Jon.