wannabe wrote: The prime reason is that the 172, even up to the newer more powerful ones will give you a much better APPRECIATION - PREVIEW for the EFFECTS of density altiude, and how it can actually cause a sickening - sinking feeling in the pit of your stomach. The 182 will usually "power out" of most of what you might encounter on an inititial High Altitude check ride. Could leave ya overconfident.
This is very, very, good advise. The purpose for the Mountain/Insurance checkout is to demonstrate the affects of density altitude (the accident database demostrates why insurance companies require this). A Skylane at 6,000 MSL, even on a hot day, with just a pilot & CFI will not do this. There is still too much excess thrust.
I moved from Iowa (where I learned to fly) to Sacramento in 1984 and immediately joined the Natomas Flying Club. Of course I wanted to go fly in the mountains, but needed the Mountain Checkout. The club had both a 172 & a 182, but the chief pilot required mountain checkouts be in the 172. I have a very vivid memory of the long take off roll and flat climb attitude flying out of Truckee, it really made an impression on me.