Modo is a young software so far, but i think it’s worth its price. and it will be worth even more as time passes.
when i talked about Modo and Lw in my comparison, that’s the current situation, in wich Modo takes advantage of being young over Lw modeler with several good things: modern structure, expanadability, good UI, n gons and edges, well tought selection system, and modelling toolset and so on.
and at the same time needs some of the great advantages that Lw modeler has with its plugs and that only a bit more time of development will bring for sure.
even if it’s not SO distant from Lw modeler now, it doesn’t mean it will be not very evolved as time passes.
so, if you have the money and like modelling go for it, because it will keep evolving and getting better in time for sure. also because that’s what we expect fom Lux guys.
also, SDK is not avaiable now. but when it will be avaiable, cool plugs for modo will start popping up. 
lw 8 so far is not so different from lw7.5 and you’ll be able to upgrade in the near future as well, if you need it for rendering and animation.