Fred Asbell teaches instinctive aiming, but his style of shooting is not the only style to use instinctive aiming. For example, Rick Welch also teaches instinctive aiming, but his style of shooting is to stand up straight and hold at full draw for about two seconds before releasing the arrow.
If you want to learn the Asbell method, which is to release the arrow as soon as you come to full draw and anchor, I think it is a good idea to learn it with your 45# bow. It might be easier to get a clean release with a 55# bow and you won't want to hold it at full draw for very long, but you will probably learn the techniques better with the lighter bow.
Anchoring for 5 seconds does not necessarily mean that you have to have a poor and static release. Although Rod Jenkins does not aim instinctively, he does hold at anchor for several seconds, and has a good dynamic release. He does that by learning to hold with a balanced pull at anchor, and then when he's ready to shoot the shot he increases his back tension until the shot goes off. He also shoots with a lighter weight bow than your 45# bow.
I would encourage you to continue to learn the Asbell method, but don't throw out other methods you have learned, because the best method for you may be a combination of different things you have learned.
I would be interested in knowing how well someone could learn to shoot instinctively if they used some other aiming method previously. I learned to shoot instinctively first, so it was easy for me to ignore the point of the arrow, because I was never inclined to notice it. After I began to incorporate gap into my shooting for longer range shots, I found that over time I began to notice the arrow tip more and more at shorter and shorter ranges. Now it is hard for me to ignore the arrow tip at any range, and I might just have to bite the bullet and become a pure gap shooter at all distances.