The back bevel is not the edge, and doesn't necessarily affect the durability of the edge at all. Look at where the edge bevel meets the primary grind. You can probably feel the "hump" with your fingernail. Sharpening at a lower angle, but not all the way to the very edge is going to smooth out the hump. The edge stays the same. You can also reprofile to a lower angle all the way, and then put a "microbevel" at a higher angle right at the edge. The first way increases cutting ability by reducing drag (the edge cuts, everything else just adds resistance), and the second way does, too, but with the added benefit of a thinner edge (cuts better, less durable), and a narrower final bevel for easier sharpening.
One or the other is always going to make an improvement in how your knife performs, though the wider edge bevel may not look that great.
You can always try it on a cheap knife or beater and see what kind of difference it makes before doing it to other knives. Your knife will definitely cut better, and you may see an increase in edgeholding.
It's worth trying.
If you're not getting a shaving sharp edge, that has nothing to do with the angle. It's because the two bevels aren't meeting at a point<<<that's all sharpness is. You might try marking your edge with a marker and sharpening, to see where your bevels aren't going all the way to the edge.
