It's technically 3k feet, but the last 500 ft or so pretty bumpy and a slight upslope on the latter half of the strip and really only one way to take off and land as there is a mountain off one side. So regardless of winds, one direction Luckily winds are usually straight crosswind on it because of slopes around. Upslope to the left, downslope to the right. 
None that I could discern. Really good addition if that short landing is important to you.Mainly a relatively short grass strip my parents have.
But given the not totally smooth nature and everything else, the less time spent on the ground rolling the better
Any noticable affect on cruise?
In my 180 knot plane I didn’t notice much (if any) loss. Different types maybe are more influenced by them?
Depends, if they disturb the smooth airflow over a laminar airfoil, they slow you down. On a golf ball, they actually help make it faster. Remember that scene from Howard Hughes movie where he wanted all the rivets to be perfectly flush?
But this time just jumped off like a normal, faster takeoff. Landed it slower than normal too and was down to 52 on touch down and still had some authority left and a gentle touch down. Normal stall dirty is 55. Granted, was at half fuel at the time and only a few hundred pounds on top of that, but still. Slowest I've ever landed it and I still had some wiggle room. I'll take it up sometime soon and play with some stalls and see how it does and update for anyone interested. But the extra authority when slow is already worth it.
After I had the VGs put on the Commander I was out doing slow flight and practicing stalls and on flight following. ATC called me and asked if I was OK as I was showing ground speed under 5 knots.Just an update, got the VG's on and very impressed so far. Haven't been able to put them through their paces yet (just two 1.5 hour flights), but definitely very noticable additional authority on the controls when slow. And just for fun rotated at 65 instead of 80 like normal as per the POH and normally doing that really have to force it off the runway. It will fly, but doesn't want to.
Also no discernable change in cruise. 140-150 knots at around 9k ft and leaned to 10 gallons an hour same as always. If there is a difference there, it's negligible.
The Arrow III Turbo really shines up at 15k+. 
It's an Arrow III Turbo with all the speed mods.
If I run it closer to 12-13 gallons an hour it actually boosts it about 5 knots on top of that typically at that altitude. But running it at 10 gallons an hour runs a bit cooler and only sacrificing about 5 knots or so for the fuel savings and cooler temps. Winter time if I'm in a hurry and on a long cross country of 4-5 hours (it has the 72 gallon tanks) I'll sometimes bump it up as the temps stay pretty cool then no matter what. But otherwise 10 gallons an hour is the sweet spot for cool temps, fuel efficiency, and speed.
Up higher it goes a lot faster.
But mine is the Arrow III Turbo variety with all the speed mods, which has been faster than I was originally led to believe before buying it. Even the old owner undersold its speed, though he said he almost never took it up past a few thousand feet so wasn't sure its speed up high. Seemed a little odd to me at the time, but his quoted speeds down low were about right. Take it up to it's upper envelope and it gets really fast.
I'm amazed at what flying around with the stall horn blaring @ 3K has done for my landings and I still get the same last foot practice going home.
… and improve sexual prowess and skill with crossword puzzles.
… and improve sexual prowess and skill with crossword puzzles.
Since to my knowledge no one has ever done independent professional performance tests on any of these add-ons, and an owner who's just dropped a lot of money on them really wants them to work (and will probably see what they want to see), it's hard to trust that there's a practical difference. None of of the aviation publications has an incentive to drop tens of thousands for professional tests that might accomplish nothing but make their advertiser's products look bad.
My WAG is that 10% of them actually do something useful, but we don't know which 10%.
To get the STC, all they have to do is demonstrate that it does no harm. There's no validation at all of any performance-enhancement claims. I could get an STC to for putting lightning-bolt decals on the side of your windows to make the plane go faster, as long as I convinced the FAA that the decals didn't harm the plane's flight characteristics.
The FAA lets them publish new V speeds for Senecas (including lowering Vmc by 9 mph). They have the ability to change the marking on your airspeed indicator to reflect the new numbers. They also allow a 168 pound increase in the MZFW. You may be right but I find it hard to believe that the FAA would allow them to let owners change critical indicated airspeeds and load the airplane 168 pounds about the certified POH ZFW without having demonstrated that that was tested and safe.
I highly doubt that there’s no validation, even for airplanes for which they don’t publish performance changes.
It’s been in the Limitations section of STCs for as long as I can remember that it’s the responsibility of the installer to make that determination.
