I always played double inverted before switching to modern defence a couple of years ago, inspired by the beauty of a classical defender at my previous club. I started with OX pips played and finished last league year with Palio CK531 OX on a Victas Koji Matsushita blade which is probably quite close to Matsushita Pro blade. I did try Palio OX on other (defensive) blades and the difference was quite big. See f.e. viewtopic.php?f=43&t=21085. I also tried some balsa blades but didn't like them at all. After last year's league I switched to Curl P1r 0.5 to be a little more stable and deceptive in long defence and to be able to create my own spin. My next experiment will be Feint Long II 1.0 on the VKM.

1) Blade: I chose to stay away from balsa blades and I also don't really like the combination hard + very stiff. Why? Because my looping was a lot better with the softer or flexier blades and so was my chopping ability. If looping is one of your core strengths, I would choose the material that maximally supports it. The question is 'what do you really want?'. More 'disturbing potential' and staying close to the table while attacking weaker balls? Or modern defence and mainly loop, fish, chop a bit further away from the table? You can do both very well with Palio OX on VKM (and so I assume also on MP).

2) OX or (thin) sponge: Coincidentally, I opened a thread about OX-chopping technique yesterday: viewtopic.php?f=71&t=23929. For me, the transition from Palio OX to Curl P1r 0.5 wasn't too hard. The Curl's sponge is very hard and thin. But I had to change my chopping stroke a little. With Palio OX, I had a shorter chopping stroke and I moved more horizontally. It wasn't necessary (and wasn't easy as well) to 'make' the spin because the pips are non-grippy. Now, my opponents missed quite some loops by sending them long, mostly because they assumed my chops had backspin, but in fact there was little spin or no spin. And, by adjusting the chopping stroke I could manipulate the amount of backspin a little bit (no spin versus little spin).

Biggest difference with Curl 0.5 is that my chops CAN be heavier and produce much more backspin but NOT with the same stroke I made with Palio OX. A fuller, longer chopping movement, bit more vertically (especially on harder shots) can create a lot of backspin. A second advantage of the Curl 0.5 is, when pushing close to the table, I can now create my own backspin which makes it harder for the opponent to attack it. A third advantage is that I can attack easier with the Curl or play an easier 'open' game. The biggest disadvantage with Curl 0.5 is that my (passive) blocks no longer feed reversed spin back to the opponent and can be punished easily. For me however, this disadvantage is outweighed by the benefits...

maybe a slower pip would help?

I would say that XiYing 979 is one of the best for ox chopping (but I guess P4 would be good as well). It has a very thick base sheet, feels almost like it had a thin sponge.

There are some good examples of OX-choppers. Let's collect them here and discuss viability for modern defence, specific technique and strategy (compared to sponged chopping)!

One of the big names chopping with OX LP (Palio CK 531 OX) is Sun Jian Fei: viewtopic.php?f=35&t=12740

Training lesson, part 2 (part 1 discusses attacking and short game with OX LP):

Doesn't Tomas Mikutis also chops with OX pips?

No, he does not. He's playing with 0,7mm sponge. Actually most of our better players play with 0,5 -0,7 sponges.
There are no choppers with OX. I could be the first one if I tried that

Yep, indeed. I updated Mikutis material in his thread some weeks ago: viewtopic.php?f=35&t=15511&start=15. Can you confirm if this is his equipment to date?