If I may applaud from the cheap seats, as someone still working my way through the newbie stage, Jim and Lugia's wisdom is mighty welcome. That priority/ratio model is a helpful guide.
I meandered from 5U into euro and wound up with a hybrid rig in which the lower-functional-density 5U modules often serve as support players for the higher-density euro devices (e.g., I quickly discovered that the Synthesis Technology E370 needs a veritable army of modulation signals to live up to its full potential). I can't claim any intelligent foresight for this, but as a pleasant change, my ill-guided bumbling through life worked out rather nicely in this instance.