I've also got a side bet going that the new Iconic Past Life Feats will not be a requirement for the Completionist Feat because they're not true "Classes". If it turns out that I'm wrong, then that just means that my next 4 lives will be to cycle through the Iconics first, picking up Iconic Past Life Feats and Epic Destiny Past Life Feats in the process.
At the end of the day, choosing to spend money to accelerate your progress through a life is your choice (or skip from 8 to 18 in the case of using an XP stone with a full set of XP boosts running). Equally, deciding that you want the benefits of Epic TRing will also be your choice. If you choose to do one to help you achieve the other, that's also your choice. You're also free to just ignore the whole Epic TR option and just have fun with your Completionist with maxed out Destinies and hope that things change further down the line.
The one thing that you don't mention is Turbine's proposal to wipe your ED XP on a Heroic TR. That for me has to be a no-go. We must keep the option for characters to Heroic TR and continue to gain their Past Life Feats with an option to do some work on their Epic Destinies each life without any loss of ED XP. Whatever option Turbine go forward with, it should only be Epic TRing that would affect your ED XP.