Interesting. I also own the HW50 and I put the Optika5 2-10x42 PA w/ Z-plus reticle on it. Yes, the holdover/hash marks are very fine and difficult to see in low light and/or woods environment. However, the large central dot is great and allows for very positive and fast aiming.
Additionally, I primarily use my .177 HW50 for squirrel hunting in the woods at 30 meters or less 90% of the time. This means that with a lighter pellet zeroed at 20 meters I don't have any holdover from 10-30 meters which is perfect. If you plan to stretch those shots out to 40 or 50 meters regularly then I would probably consider a thicker reticle of some kind so that you have usable holdover marks.
For plinking, the reticle is awesome...unless it gets dark. I found the reticle to be great for punching paper where it is quite visible and effective...ALSO...
The Z-plus reticle is an MOA based reticle, as I recall, which is one of the reasons that I almost went with the standard Z-plex reticle as I only use MIL drops. It just so turns out that the SFP reticle can be used for either MIL or MOA depending on the magnification. I discovered that at just shy of 10X when the adjustment mark is just on the right side of the "0" of the "10" on the mag ring...that the reticle is a perfect one MIL holdover reticle...very reminiscent of the popular "mil-dot" reticles that are basically a duplex with 5 dots at 1 mil intervals. This discovery was great because now I effectively have a MIL based reticle! To say I was excited at this discovery is an understatement! What is great about this is that at 40 meters with my HW50 the drop is about exactly one MIL...easy peezy. Now I have a 40 meter sniper rig...squirrels beware!