I bought a pair of 390 boss and I weigh 200 and it feels good for me.
On a side note, I am not sure if it is my bindings or if it's a typical occurrence but my rachet on one of my bindings won't lock down. Now the day that it happened it was super cold like 10F n someone told me that it might be the spring freezing, which is why it didn't lock. Is that usually the case? Or is there something wrong with the rachet? I rode two times after that day and it "seems" to not have that problem. I also crimped the top rivet on the rachet, which might have fixed it
I have theses binding and have not had that problem. However my lean adjuster did move on me once but that could have happened on my nasty wipeout I'm not sure tho. I love these bindings if it continues to happen contact Rome and they will make it right.
As for the stiffness it's all personal but I think they are a mid flex binding just like Rome says they are. I think you would be just fine. The biggest difference between these and customes is the aluminum heel cup. This will make the romes more responsive.