good players will catch on, but as they do you vary it much much more.
While players CAN catch on, you can mindgame. This is why my dtilt ideas work. While it works for those who don't know, the two quick dtilt and immediate followup, the smart players who pick up will adjust to mainly that usage, since I've used it so safely. I switch to one hit for those who shield the second, and keep hitting for those that don't have a super quick grab and refuse to shield. the ones with a quick grab, I tend to use dtilt much less.
apply this to pkjump. You've got many ways to use it. wavebounce, forward, reverse, standstill, short horizontal, ledge jumping getup to pkjump... etc. Combine all that with the fact that you can do it after a FH or SH aerial and almost always get an aerial hit to protect. There are infinitely more variations for keeping it mixed up, and even if your opponent can see in time and shield, only a few characters can get the hit off on you as you drop down. I think you should be able to airdodge in time if you do predict that you are going to get hit by something. Almost all variations of it allow a safe end....
But on that note, if you mess up with making it an actual PK Jump, you screw yourself over. If you know beforehand that you're going to mess up, you should wavebounce the DJCPKfire or just regular PKfire to avoid as much punishment as possible by getting the most distance away from your opponent. That's what I do, because I know where I'm going to mess up.
While it is easy to catch on to and sometimes to punish, the same can be said of FH PKfire... in fact, FH PKfire is infinitely more unsafe.
What is needed when using PKjump is a knowledge of the range. If you know that, you can both plan on the timing of the bolt hitting the opponent or their shield and your followup to ensure your safety. If you get it just out of range, the opponent will be like "WTF? LOL" sometimes and you get an aerial hit. Higher up players will take that opportunity to get off an aerial, so immediately airdodge or use bair/nair/uair, depending on the character.
TL;DR: The same can be said of everything; all options are predictable when known, but your ability to vary them is what makes win out of it. Know your options with your moves and how to transition between them well. Know them in and out, more than you think you already know them.
EDIT:
Oops... I was dumb... wrong focus.
Congrats dude! At least you're at 9. Higher tourney rep than I ever got (I've gotta get to more tourneys so I can see how well I can do...)