I have tried following everything online to see whether a saver fare is worth 7.5 or 15 Tier credits. I am getting close to Concierge so every 15 points is important.

My assumption is that it was here from everything I read.

Also I assume if I book a saver and quickly call to upgrade to Aer Club that I would still get hit with the 40 euro charge per flight.

I am currently sitting on 860 tier credits with all flights booked until mid January with the exception of a short break which I will book advantage to get me 80 meaning I will have 940 Tier credits with the end of March as my due date.

I will have a few more flights between Jan and April but worst case scenario I jump on an Aer Space flight for around 400 euro to get me Concierge. The investment would be clearly worth it.