My old MirroMatic pressure cooker was over 40 years old & I decided it was time for a replacement.  Instead of the old all aluminum pan I decided to get the stainless steel pan for ease of cleaning.  What a difference!  The aluminum core on the bottom provides the even heating, & the stainless steel makes for the easiest of cleaning.  I really enjoy the rocker weight on top instead of my old weight with 3 different pressure settings.  This one is so much quieter, too.  Tonight, I'm making Swiss steak with only 18 minutes of cook time.  You can't beat that.  The cool down time is much faster than with the old aluminum pan also.  I should have bought this years ago.