I used to use the brass inserts (and in fact most of my arrows still have them) But recently I have gone back to the aluminum inserts that came with the arrow For 3 Reasons:
1. Cheaper – why pay for something that you get for free with the arrows?
2. More FOC – by going back to the aluminum inserts, I can make my broadheads heavier for the same arrow and increase the FOC just a little bit more.
3. Arrow Footing – I put a 1.25″ (or so) aluminum collar over the end of my arrow shafts which is often referred to as an external footing. This increases the strength of the shaft so that the extra strength of the brass insert is no longer necessary.
Note – the 55-75 shafts are about 2 inches longer than your 35-55’s. I like the extra length. Don’t forget to consider that in your plans…