I've had very little maintenance with butted, 4in1 scale shirts overall. Though the extra rings add weight, they do reduce slippage. The most common spots for occasional slipped scales are around the collar where you pull it off of you, and the middle of the trunk where you bend over. Depending on your pattern, seams can also be a pain point. For example, a 45 degree seam is normally held together by one ring attaching a pair of scales. You can strengthen that seam by covering it with scales and adding the extra rings to keep them laying straight. Using stiffer stainless steel rings was smart, you'll have fewer slips than with softer metals, and less trouble maintaining the armor.
I was also one of those 'weirdos' that wore steel for larping, since I got more points for the armor than aluminum or plastic. (I usually skipped a shield, so the extra points helped.) You will have to take care to build up to all day wear. Also, you might feel fine for a good while, but by the time you realize you need a break, you're already in for a good deal of back pain and stiffness later. So take the time to condition your core, lower back, and upper back between your shoulder blades for the additional weight. Pay attention to your knees as well. Even if well fitted, you still have to generate more force than you may be accustomed to in order to get in motion, to change directions, and to stop.
Those steel scales are going to require a good bit more maintenance than aluminum or stainless steel scales. Remember to scour and oil them periodically. I also use Windlass Rust Blocker on my old galvanized steel ring and hardened steel scale shirt to extend the time between cleanings.
Agree on that point. Unless the LARP organization specifically requires steel, you'd be far better off with anodized aluminum. With butted rings there is inevitably going to be regular maintenance needed, but putting the shirt on a diet would minimize that.
Unfortunately TRL recently mentioned that the welder was out of stock and there would not be more made, so that's out.
As you say, the main stress on a vest used in LARP is its own weight. With that in mind, do you really want to use steel scales? They are very heavy (putting stress in the rings... and on your body), and they are likely to rust. My favorite combination for very durable LARP armor is aluminum scales with stainless steel butted rings (using the standard weave for scales). The rings are fairly heavy, but the lighter scales mean that vest will be 15 pounds instead of 50 pounds... and it will be much more durable for larping.