The MK9 in a Silent Thunder will go virtually unnoticed on your hip. The single clip is solid and easy to take on and put off. The MK is a great little gun. Like you apparently I'd wear an eskimo parka in Phoenix in mid summer rather than pocket carry but many really like that option.
Keep in mind the MK to me anyway isn't a range gun, so you don't need to shoot it 300 rounds a week, shoot it often to get proficient and stay in tune but you can use something else for range for fun and practice.
Again this is just me but a c0cked and locked gun, even a 380 ain't going in my pocket, just not gonna happen.
You sound completely sold on the Sig and if thats the case theres probably no saving you. The PM or the CM would be even more comfy to carry over your MK and you could do the pocket carry if you had too or wanted to.
And they, the MK, PM and CM are all 9's. That says plenty in my book.
I think the minimal size improvement for your big hands would be negligible going to the K9 and if IWB works for you step up to the PM45 or the P or CW45. If your body is scaled to the size of your hands you can hide a pretty big gun with the right holster. I'm just a little bitty guy, you could whoop me easy without your lunch and no nap but I conceal a 1911 and a PM45 pretty easy. (warning) I am kind of wirey though.
Bottom line it's yours choice to make and we'll help ya whichever way you go. Your the one thats gonna live day to day with your choice.
The MK is a just a sweet gun too, I'd be hard pressed to part with that one.
In Memory of Paul "Dietrich" Stines.
Dad: Say something nice to your cousin Shirley
Dietrich: For a fat girl you sure don't sweat much.
Cue sound of Head slap.
RIP Muggsy & TMan
"If you are a warrior legally authorized to carry a weapon and you step outside without that weapon, then you become a sheep, pretending that JOCKO will not come today."