I had the original 8x42 WP for about ten years and loved them. In my opinion, alpha sharp in the center, but trailing off fast from there. Not a big deal for birding, though. My guess is the current 8x43 ED is about the same in terms of center sharpness (?), significantly sharper off axis. The fact is, aside from the eyepiece Pentax hasn't really changed the basic design of their top of the line binocs in over ten years (same FOV, same eye relief, same basic housing--very conservative).
I now have the 8x32 ED, which is not quite as sharp as the old 8x42 WP, in the center, but is significantly nicer off center (that's the eyepiece). Other differences? MUCH nicer color, whether due to coatings or ED, or both. The old 8x42 WP's were bluish in comparison. Pentax ED really does this part right, I think, although the color may be a touch warm for some. My 8x20 Ultravids are ultra neutral in terms of color, but I actually like the warmth of the Pentax. My Nikon 8x32 SE is a touch warm too, but not quite as much as the Pentax.
Overall, I like the Pentax 8x32 ED. Very bright, great color, virtually no CA. I wear glasses and the 17mm eye relief is a tad less than I would like. Pentax has the eyepiece recessed more than Leica, Zeiss, etc., so Pentax's 17mm, in actual use, is LESS than my 8x20 Ultravids at 16mm. The Ultravids, in fact, have ~1-2mm more relief than I need. Eyecup design, as much as actual relief, is a significant issue for eyeglass wearers
The Pentax doesn't have the sublime view of the 8x32 SE's (perhaps no other binocular does) but it's a good all-around binocular. Heavy-duty housings and rubber armor for sure. I take them kayaking and don't worry about them.
I've owned five Pentax binocs over the years and have always been impressed with the quality. Always a solid, dependable feel. The Chinese bins are changing everything, though, so the future is up for grabs.
Mark