If all you want to do is cut foam, balsa, and light ply, you could save yourself a couple grand by getting the 80w. That's what mine is and it has plenty of power. The tubes and power supplies are cheaper too if you need replacements. For fine engraving make sure you get a 50mm lens (or 54mm, whatever they are called). I'm really impressed with the fine engraving detail I can get, and the kerf is narrower for cutting than with a 100mm lens.
Go for it! You will wonder how you ever got along without it, and the local parts and support is a bonus too.
Hope that helps,