Susi Air
Hi Zeebee , the Susi Air Porters are almost new 2 to 4 yrs from memory.
YouTube - Porter Flying in Papua
Descents
http://www.youtube.com/watch?v=AD1xBMthXBs&feature=related
Another operator tweaked their Porters beta and could descend vertically and come down in formation with the skydivers at 10,000fpm but IF it ever came out of beta they were going to go through VNE
We decided 2.5 min / 6,000fpm descents were a good enough balance between efficiency and safety !
In link 2 the descent starts at 12,000 ft (not 14,000 as it says on the video title) and thats a pretty typical ride down (except he leveled off for a moment at 1,500ft) and he took exactly 2.5 mins for the wheels to touch the runway.
You can see the prop really starting to bite the air at around 9,000ft as the air gets denser. Above 15,000ft there is very little propellor brake effect.
You can see the Porter is quite responsive when it's LIGHT and really bleeds off that excess speed before landing when you pull the nose up.