Well all.....
As I have stated earlier (in this thread) I am a musician and pro audio guy. My main rig is a MacPro. I am upgrading my office machine where I do some lighter audio work and wanted a portable rig as well. I am coming from a mac mini which is kind of a dog but is also very quiet. Reality though is I never asked it to do much. I am very sensitive to fan noise and after using a 13.3 2011 i7 for a week I really wanted to make sure it was the right one for me. Whenever the fans in the 2011 would ramp up it really had me concerned. After reading this and any other thread I could find it seemed as if the 2010 15 i5 was the one to get. So I did...... And after a day of testing the two in my target application (Pro Tools) the result for me is more than a bit surprising!! In the spirit of give em the facts first I present the following............ I will put my comments at the end......
Notes....... about "data"..........
Even a 0.5dBA increase is clearly audible
All work done in 10X10 office with ProTools LE 8.03 and Handbrake
Sound Level meter = SPL-8810 (nothing too fancy)
Sound measurements taken about 2 feet away from machine -
machine about head height WRT sitting position
All data is my own work.... YMMV.....

Room ambient noise ~33dBA Temp~23degC
Wish all my nice formatting would come out better
The proTools test always have three variants 1) with 5 dverbs 2) with 35 dverbs and 3) with 55dverbs. All of these have signal going through them.......
2011 13.3" Core i7 2.7
@2% load SAfari, mail 52degC 2000rpm
Note: at 2000rpm I can hear the spinning Hard Drive but not the fans! SSD upgrade in the near future....
@100% load Handbrake default settings for m4v
90degC in 15 seconds,
6200rpm in 25seconds,
stabilize ~90degC for CPUA, CPU1 average 98 to 100 (41dBA)
Was more like 85 after 30 minutes..........
Encode Angels and Demons ~40min ~100fps
PTLE 8.03 256 buffer 3 proc 99% 3Audio tracks, 15instances EQIII 7 band, 2 Boom, 1DB33, 1 miniGrand, 1Vaccuum
@5dverbs 21% system load -----73degC, 4500rpm 35dBA
@OPen Lid --------------------------77degC 3200rpm 33dBA
@35dverbs 35% system load ------76degC , 5600rpm 39dBA
@Open Lid----------------------------82degC, 4000rpm 34.5dBA
@55Dverbs 42 % system load-----80degC, 6200rpm 40dBA
@Open Lid---------------------------85degC, 4800rpm 39dBA
2010 15" Core i5 2.4
@2% load SAfari, mail 52degC 2000rpm
@100% load Handbrake default settings for m4v
93degC in 60 seconds,
6000rpm in about 2 minutes
stabilize ~82degC for CPUA,
CPU1 average 83 (40.5dBA)
Encode Angels and Demons ~50min ~average of 80fps
PTLE 8.03 256 buffer 3 proc 99% 3Audio tracks, 15instances EQIII 7 band, 2 Boom, 1DB33, 1 miniGrand, 1Vaccuum
@5 dverbs 32% system load--------68degC 4300rpm 35.6dBA
@OPen Lid-----------------------------72degC 3000rpm 33dBA
@35dverbs 51% system load-------74degC 5000rpm 37.5dBA
@Open Lid-----------------------------74degC 3480rpm 34.0dBA
@55Dverbs 67 % system load-------75degC 6000rpm 41dBA
system barely able to handle (CPU overage)
@Open Lid-----------------------------78degC 4000rpm 35dBA
1) Biggest discovery was just today. In clamshell mode (I was always running it with a 24" LED display) the cooling mechanism on the MBP is much less effective. Once you open the case the absolute temp does go up a smidge but the fans go down a lot! If I would have tried this earlier I never would have gotten the 2010 (no worries though I can return it

)......
2) For loading up the same session in each machine the difference in fan noise is really very small. Temps on the 2010 are a little lower but for me as long as Apple knows what they are doing and stand behind the 2011 (think applecare here) then higher operating temp is OK with me.
3) The 2011 is half agin more powerful than the 2010 in ProTools. ie.... 1.5 times the system load (on the 2010 vs the 2011) for the same session. For this machine the 35 dverb test is probably overkill for me. Somewhere around 5 to 10 aux plugs and six or so Virtual instruments and then 10 to 20 real tracks is where I will be. The 2011 will handle this let's say 20% load with minimum fan speeds. Done deal....... the 15 goes back tomorrow!
4) Hi Ho Thunderbolt.........
5) Yes for a 40% load on each machine, the 15 is quieter....... but the 2011 is doing 1.5X the work!! Much more useful for me to look at relative loading for the same work........
OK..... a week of agonizing and now I am decided........
I am sure many will find flaw with this methodology but that's the way it goes. Best of luck to all......
-Lee