They are excellent stable (straight) high speed drivers. They are like perfectly seasoned Wraiths, which isn't that easy for me to find in my Wraith collection. A perfectly seasoned Wraith, to me, is one that flies pretty straight when thrown flat or with a slight hyzer flip. They fly similar to Westside Swords.

I have one Apex in Diamond and one in Platinum.  Both plastics feel absolutely excellent- flexible and grippy. They land next to each other. They aren't super-overstable. They fly best when I am not trying to throw max distance but when I just want to make sure I reach a hole that is a little far for a fairway driver (e.g., work-horse driver).

Backhand, I throw it flat or use a slight hyzer flip to get a straight shot with a little fade. Forehand, it flies the same (straight with a little fade) but I use a little more hyzer.

The Apex seems perfect to me. I'm learning that Gateway has nice drivers and plastic options. 

The Gateway Apex is a really nice distance driver that flies pretty stable, but with the ability to work the disc as well. It reminds me a lot of a beat in Destroyer. You will get some controllable turn and decent fade at the end of the flight, making this able to get out to great distances. Overall, a very nice disc.