I think I mentioned above that I have Qi's and A8's... the A4's are simply the ADEL tech (now APEX ?, after separation from Asius) version of the Qi's.
I've concluded from using both that the ADEL's mostly act like having ambient ports, without the loss of bass that you get with a full seal, and
NO ear fatigue... !!!
That said.. BOTH sets can produce stupid/silly levels of bass, due to 2 and 4 BA drivers in each.
They can also produce ice-pick treble - if you desire.
I have also suggested to others, that if they are unclear/undecided.. call Alex at 1964 and explain your needs.. they are very helpful.
However, if budget is an issue, I would not hesitate to suggest the A4's...
The difference between the 2 is the Qi's are full-seal closed.. I needed to get used to the difference in bass between the 2.. it took a while.. there's no LACK of bass in the A8's, but the bass mix levels I run with are a little higher than I did with the Qi's - so put that down to the "A" technology. They fit fine, are really comfortable, and I often wear them between sets as the DJ music is way loud at most venues!! And yes, I can happily talk with folks with them in..
Being a first time user, it may take you a while to adjust to them.. inserting into your ears for #1 LOL

... it's a VERY different experience for folks used to a "live" stage with wedges and I've met more than a handful that cannot adjust. But if you use phones now, the swap will give similar, but BETTER results.
In case I haven't mentioned it before I REALLY LOVE BOTH SETS OF 1964 EARS .. but the A8's are awesome.. repeat buy in a heartbeat !