The 7800 does have a more vertical thumb angle than the 7490, and the Ventus/Vision has a more vertical thumb angle than the 7800 does. According to Vaughn, if you're noticing a lot of puck marks on the finger side of the pocket, then you'll want to stay with the 7490. If you're taking a lot of shots off of the thumb mold, then you'll want to move towards the 9500.
If you're looking for a Vaughn glove with the most vertical thumb angle, then then T5500 TG glove would be the way to go. The link for that glove is below, and I've also attached a video for it as well: