Some reviewers and customers have said they actually like the tech and feel in the T300RS more than the more expensive "big brother" T500. However, as you noted the 500 at least is a completely viable full set.
I will just reiterate that if the T300 really is as good as the 500, and its pedals suck, then the cost is the same after you add some Fanatec pedals or upgrading to the T3PA's that come standard with the 500. You cannot upgrade during your order and mix-n-match with the T300 Wheel + T3PA's (major annoyance, but if available right now I wouldn't have my CSR-Elites)
The above info about adapters should be preceded by this caveat. The one by basherboards has a long waiting list of at least 2-3 months, though his production may pick up at some point. In fairness, he did just respond to an email asking for an update and mine will be produced within a week or so...
I might be back before GT Academy is totally over...