I managed to obtain the Shogun-Guard upgrade for Corn yesterday, and I gave him a try in Mount Steep to give the upgrade a test:
https://gameclips.io/DefenseGuy35/28d2c1ea-1c7e-403c-b997-61983a0313e2 (trying out Shogun-Guard for the first time).
My experience with this upgrade is as follows:
I love it! ❤️ It changes the character's primary by a lot. The increased damage output (especially with critical hits) is awesome and it’s easier to take down zombies (especially browncoats). Using butter beacon (which I noticed you can activate without letting go of the shield) is really good for further improving your already increased damage output, especially if you need to vanquish a zombie quickly. The lower speed and ammo of your primary isn't that costly, because the speed is still decent and the reload is quite fast (I'm not using Rapid Recob as of the moment). The shield is excellent: being able to shield and shoot/reload (or use butter beacon) at the same time is a very good feature. I have limited mobility when the shield is active, and the shield has low health, but it's an excellent add-on, the cosmetic of the shield is awesome, and it makes it easier for revives (which I really like doing).
I also gave the Shogun-Guard a go in Rando Ops (just so happens in my first game I got spawned as Kernel Corn, with my Shogun-Guard equipped), and it worked very well for me, even when my team was being surrounded by enemies. Currently, I'm also using Refreshing Revive and Low Life on my Shogun-Guard Corn build, but I know that many players use Rapid Recob in conjunction, so I may consider using that instead. Overall, loving this upgrade! 😃