Multiple Master Sets and Why?

[Necro]

So I'm very new to Heroscape, but I've played many a other strategy game. Heroscape seems to combine a bit of collectability and a lower cost than the Warhammer games, while being much more accessible.

However, what I'm wondering is what is the purpose of having dozens of Master Sets? I currently have 2 SotM and 1 RotV. Since there are few common armies in each of those, you're basically getting them just for the terrain, correct?

Just want to know if it would be beneficial to grab a $20 RotV (not Edition 1 ). If I could sell of the characters on Ebay it would be an easier decision, but I'm debating if two Expansion Packs of armies/hero's wouldn't be a better investment....or trying to find another kind of expansion pack with diff. terrain.

Thanks for the advice for a new guy! (and sorry if this has been covered...I can't find a search function at all and I went a few pages back looking for something similar)