Ridgid strength is different than load strength. Do a bend test like you do for a welding certification use similar thicknesses of metal and then apply pressure in the center and watch. I miss spoke when I said soft it is as Jon said brittle that is why the corners of the philps heads chip out. But under load SS will snap where basic steel or 4130 will give and bend. If you want Ridgid strength use composite material as in graphite composite which is amazingly stiff or ridgid.
As I said before the biggest problem with hardware is that the faster and the attachment or holding material are different materials. So using Stainless which is anti corrosive but threading into a steel nut plate causes dissimilar corrosion. This is the beauty of the anti seize it coats and fills the threads giving you a protective layer between the two different metals, which keeps out water and air. And in most normal heat areas will stay moist for easy removal.
Anti seize can be of several materials, copper,silver, anti seize which most people are familiar with. But use can also use beleive it or not Milk Of Magneisa, just make sure it is the unflavored brand so you are putting sugar into the high heat area.
We used this on ignitor plugs on General Electric jet engines like J79 used on the F4's and other GE engines. These plugs are fed 28000 volts DC to ignite the engine so the threads do get abit warm. And these areas of the engine can reach 1200 degrees C also from the burning fuel and air passing by.
But for our use the only area for continuous heat cycles would be the fire box, the rest would be a moisture concern so SS hardware with proper anti seize compound will work fine. I think for personal preferences I like the bolt heads of 6 or 12 point head style, and torx or Allen drive screws, which hold the drive bit into the faster much better.
At the end of the day what you use is up to the owner and your price range .
I bought a 2014 performer and was replacing the table to a metal one. And one screw was frozen into the rivnut, steel screw and aluminum rivnut. I used SS Allen drive screws when I installed the table with anti seize. Now should be able to remove anytime.
After 45 years in my bussiness this is just natural to me and abit foreign to others. Sorry for the long post and I want to say I had no intention of berating anyone, just trying to expand on avpoint and I am no engineer either I could also be wrong I only know what I have been taught and read in the maintenence manuals. So if offended anyone I apologize.
. But, it does seem to me that the negative issue with stainless is its brittleness rather than it being soft. I do know from working on sanding stainless flat panels that they are VERY hard to bring down even a little, whereas regular steel will sand much easier. On the other hand, I once worked on a Crown Verity all stainless grill. Even the axle was stainless. But, the axle broke right in half. I really doubt regular steel would do that unless it rusted completely through.