Hey there! Congrats on the Mark IV—it's basically a tank, but treat it carefully. I actually had a cheap card corrupt on me during a client shoot once, and honestly, it was a total nightmare... so now I'm super cautious. For CF cards, I literally won't use anything but the SanDisk Extreme Pro 128GB CompactFlash Memory Card 160MB/s. It's pricey but worth it for the peace of mind. Regarding the grip, I'd suggest:
- The Canon BG-E20 Battery Grip is great for balance with heavy glass, but it adds a lot of bulk tho.
- Make sure you use genuine Canon LP-E6N Lithium-Ion Battery packs.
- Also, definitely get a screen protector like the Vello Screen Protector for Canon 5D Mark IV. I dont trust third-party batteries tho—I've seen 'em swell up and get stuck, which is a massive headache. Better safe than sorry, right? Anyway, gl with the new gear! peace

For your situation, I’d highkey suggest looking into the Lexar Professional 1066x 128GB CompactFlash Card for ur storage needs. While people usually suggest other brands, the VPG-65 rating on this is actually crucial for handling the 5D4's heavy 4K video bitrates without dropping frames... it's basically a beast!! Also, if ur worried about weight, skip the battery grip and get an L-bracket instead. I use the SmallRig L-Bracket for Canon EOS 5D Mark IV 2145 cuz it keeps the center of gravity directly over the tripod head when you're shooting vertical. Seriously, it's a game changer for sharp shots. Plus, the stock neck strap is kinda painful after an hour, so definitely grab the Peak Design Slide Camera Strap SL-BK-3. Those quick-connect anchors are honestly life-changing when u wanna swap gear fast. The Mark IV is a fantastic camera, basically a tank. Enjoy!! 👍

Story time: I bought a cheap grip once and it felt so flimsy, honestly a waste of money lol. Whats ur budget? Are u doing high-speed sports or just casual shooting??

Wow ok that changes things. Gonna have to rethink my approach now.