I have '14 3.8 LWB and it already has a transmission oil cooler fitted behind the front grill, which is why I didn't get another external cooler fitted. For the fan, I was told by one of the service managers at Habtoor that they can fit a fan in front of it. It's the same fan that is fitted on the driver's side behind the grill so side is not an issue. It costs around 9 times more than the solution you posted ,but apparently that's mostly the cost of the OEM part.
I guess it comes down to the driving style. I'm only using 1st and 2nd gear in manual so the gear shifts are not as often as they would be in "D".
I've not done a 0-100 by myself before or after, but the difference on road is noticeable. My drive last Friday was my 1st drive with a combination of upgraded suspension, kill switch, and tuning. Overall the power delivery has improved tremendously but I'm not sure how much of it I can attribute to just the tuning.
Pajero's after 2007 are known to have an upshift issue when you're climbing big dunes or pushing the rpm's even when driven in manual mode. The advantage with tuning is it takes care of this problem.
Tuning was never about the fuel consumption for me. This car is 80% for offroad use so the tank never really reaches empty to compare the fuel economy.
This is an interesting option. I'm sure it will be equally effective and a cheaper one as well. I'll probably stop by the workshop to talk about it sometime this week.