I mean I have read both the method books 2-3 times in completion and try to watch every podcast or anything released with him to understand his ideology as well as possible. 5th Set has proven itself 3x in a row for me personally, & I think a lot of his methods are based in both science and obvious widespread success - things like block periodization/progressive sport specificity within the macrocycle, never leaving the comp movements entirely, longterm delayed training effect LTDE based-peaking, autoregulation.
The guy has experimented a lot over time, and nothing at all has been suggested without thought. For example, pull-ups are after deadlifts because they help traction the back. Barbell rows are important, but after lots of pulling the last thing most guys are able to manage is more bent over pulling.
Swede said he has done upper back work on upper days instead and it worked fine, he just prefers to put it on lower days and keep upper days easier.
The big thing to consider is the goal of the earlier mesocycles’s MSM is to build more muscle specific to the big 3 movements. So there needs to be significant volume accomplished. If I was going to try using deficits, I would keep them on the light end. Consider that you will never ever have to pull that far down in a comp, so that is less specific than a rack or block pull (which is in a range you will ALWAYS have to pull through). I would say unless you are glaringly weak off the floor, it’s probably not the best choice. Also consider that paused or tempo leg presses can be used to build that starting muscle as a general accessory anyway (one of his recommended ones).
If you do go with them, I subscribe to the Paul Carter ideology that you should just stand on the smooth side of a plate. Any bigger deficit really begins to change your body position away from your comp pull. Big deficits are good for bodybuilding and strongman, but they definitely aren’t specific to powerlifting.