The NGI Gen 2 MOD3's are pretty damn good systems, especially if you pair them with a good illuminator.

But if you have it in your heart that at some point you're going to upgrade the tubes I would recommend just saving up the additional $2500 and getting a Gen 3 system.

Upgrading tubes is not economical and its the vast majority of the cost of the system. You'd essentially be throwing away that cash. Buy the best thing you can afford and you because you'll regret it if you dont.