To really understand medium pips, you probably need to really understand long and short pips. Some short pips play almost like smooth rubber. The classic short pips rubbers were made for aggressive hits and blocks. Unless you are chopping with short pips, you’ll need to be attacking often, and from pretty close range. Take the sponge off of your short pips and you’re playing hard bat. To compete in sanctioned hard bat tournaments, your pips will have to be on the approved hard bat list, and you will have to use an all wood blade. I used to play with short pips, but I now find it a hard style that requires more energy than I can muster. After using inverted rubber, short pips seem to lack control when trying to grip the ball. 
There has been a ton of material written about how to use, and how to play against long pips. Long pips rubber comes with names like Frustration, Undertaker, Viper, Octopus, Curl, and Twister. Apparently, once pips get to a certain length, balls will tend to act differently than they would with more conventional rubber. Most long pips are excellent for chopping. Beyond that, it’s sometimes hard to explain all the possibilities of using long pips. Long pips reverse the spin on the ball, except when they don’t. They are great for blocking, except some players can hit with them. They will slow down the game, but some are quite fast. The variations all come from the bending of the pips. Some pips bend easily, and some only bend when a ball is hit hard. They can be very difficult for new players to play against, but they are not particularly easy to use either. It’s quite difficult to stay in a rally solely using long pips. Long pips players need to get both sides of their paddle in play to be most effective. This might involve twiddling Learning to twiddle can take months to learn. So, long pips can work, but they are far less potent against more experienced players. 
Now, what about medium pips? Medium pips are not as deceptive as long pips. They aren’t as fast as most short pips. Not many players use them, and there must be a good reason. One reason is that, at least in the eyes of the ITTF, they don’t exist. RITC 563 pips are advertised as the best selling medium pips in the world. They are listed on the ITTF site as merely pips out. There is a designation for long pips. Apparently 563 didn’t make the cut. There have been some professional women that have used medium pips to attack serves and make aggressive backhand drives. But, many players have felt that medium pips simply weren’t special. They did plenty of things decently, but nothing great. That is certainly a fair statement, and one that would make sense, since most players are either coming from long or short pips. The proverbial happy medium may not be there for many players, but it could be. Medium pips are far easier to attack with than long pips. They are also easier to control, and easier to learn for players coming from smooth rubber. Some medium pips are fast, and they do add a touch of deception that is missing from short pips. It is possible to chop with medium pips. A good medium pip rubber will have some grip that allows for the same types of roll shots that can be made with long or short pips. Medium pips can be used like long pips on one shot, and short pips on another. Winning can’t be done with pure speed or pure deception. It will take a more cerebral approach that takes advantage of all the good things that can be found in the middle.
I think it obvious what my opinion of people who play with pips. When when I reach the age of 100 I’ll use them to.
Use them to what? Remind me next year “when when “ you turn 100. I’ll buy your first sheet.
Most world class players that use medium pips use them on their backhand are women who block and counter drive with supreme aggression. Medium pips can be used for occasional defense, but this is not done at the world level.The former Australian world player Miao Miao used 563 on her backhand and is a clinique on using 563 ( catch her matches on youtube) . Japanese world player AI Fukuwara used Armstrong medium pips ( also on youtube).