As far as I know, changing between eco and power mode only changes the transmission settings in the tune.
There are guys like The1 who can re-write code so tunes can do so much more but if we are talking about a standard tune that it's only the trans settings that get altered.
One thing I hate about the stock tunes is it going into 4th gear at about 50km/h YUK. I changed mine so it stays in 3rd up until about 70km/h but it will lock the converter in 3rd and used no more fuel that it going into 4th (cruises very similar to a manual trans in 4th gear as both are 1:1 ratio with the converter locked). On the flip side, when I do give it a bit of gas it will unlock the converter and get going rather than having to first kick down a gear. IMHO the V6 factory transmission settings are totally wrong (unless your only concern is emissions). Small engines need more revs to create torque and prevent the engine labouring.
Power mode is the easiest way to increase line pressures a little as well as slight alterations to shift points (increased RPM's). If you want to do it properly get a tune done with increased line pressures. The other beef I have is the factory service interval for the automatic transmission. I'm fairly damn sure that my owners manual says 80,000km's which IMO is far to long. New trans fluid is almost pink in colour, once it starts to get to a dark red colour it is already getting well past it best, if it smells burn or it's brown, dump it quick. I always suggest using a white paper towel to check the trans fluid so you can see its true colour. Also smell it. If a trans has been real hot it will have burn the fluid and you will smell it.
The missus trans is still going @ 23x,xxxkm's. It's been slipping since before 100K km's but only if you give it stick and for some stupid reason when you get to higher altitudes??? (like going skiing up Mt Ruapehu).
One thing I did notice is that when fitting larger TB's you do need to increase the line pressures as you are making more power at a lower TPS setting. TPS Vs road speed determines line pressures. Factory line pressures are enough to prevent major slippage but enough slippage to smooth out gear changes. Slippage = heat and wear. Heat kills auto's as we all know.
I also don't believe the theory of the factory inline radiator trans cooler creating any effective heating of the trans fluid during cold start/warm up cycle. When you start a cold engine all the coolant in the engine cycles around the engine for the first couple of minutes, no coolant makes it to the radiator, when the thermostat does start to open, it only opens a little at first (thermostats open/close progressively to control temps) so only a small amount of hot coolant getting into the radiator which cools down fairly quickly, and the engine has to heat any coolant coming from the radiator which is effectively still at ambient temperature until it's cycled through the engine. The transmission fluid that goes to the trans cooler comes out of the converter, the hottest part of the transmission.
There are a number of guys who have bypassed the factory inline radiator cooler and only run the external cooler. They have reported more stable transmission temperatures so there is some food for thought. My own personal experience seems to back this up. I still have the factory setup (internal to external factory fitted cooler) I also have a trans temp gauge. Trans temps are generally fairly stable unless giving it a lot of stick. However been stuck in traffic the transmission temps slowly climb, the engine temps are as expected, they rise and fall with the thermofan coming on and off but the transmission temps slowly keep creeping up. The only time this doesn't occur is when I switch the aircon on and the thermofan stays on a lot longer (engine temps pulls down to the normal running temp/thermostat temp) and the transmission temp slowly comes down. Once you get moving fast enough to get some decent airflow through the front of the car the trans temps slowly start to normalise but it takes a long time.
175° F = 80° C
220° F = 104° C
On a stock V6 you run a 196° F thermostat and the thermo fan comes on @ 104° C and turns off 100° C. Hotter than the ideal transmission fluid temps recommended for a long trouble free life......