Those of you who read the FSA Crankset problems post, pretty much know why I'm posting this.
The 6600 series componentry has pretty much been phased out for the new 6700 stuff.
That equates to the 'rock and a hard place' problem for those of us with 6600 series componentry.
Question I have is: Will the 6750 compact crankset WORK with the 6600 front derailleur and is there going to be issues with the brifters (the orig. 6700 series worked with the 6600 brifters).
I've got 6600 componentry..rear derailleur, 12-27 cassette, front der. and brifters.
Much as the new 6750 hollowtech looks awesome I'm not spending a small fortune just to get compatability.
The 6600 compact double is still avail (right now) and for under $200. (no BB)
Figured I'd ask.
Thanks

Simple answer, YES, I use a similar 6750 crank, 7800 front mech setup, have used both 7800 & 6700 shifters as well, with no performance issues

The only compatibility issues you can have with the 6700 series to 6600 series is the brakes, as the use a different leverage, which can result in more cable pull / worse performance when using 6700 shifters with 6600 brakes, vs 6700 shifters and 6700 brakes.

this is the same with 5700 & 7900 series parts

If the front deraileur doesn't shift that well I have fond that the FSA compact deraileur work wonders on some bikes when the OEM didn't work as well. I found Cervelo's were about a 50 50 split on working or not.

With the new Shimano 10 speed component compatibility - you are dealing with shifters and derailleurs but not 10 speed crank/chainrings. The new generation chains are not absolutely needed and the new brakes are not absolutely needed. I have serviced new bikes with new generation shifters/derailleurs and aftermarket brakes and 10 speed compatible chains. Best results may come with all Shimano components. But as always - a good mechanic can make different combos of components work very good.

A 6750 crank will work perfectly with 6600 components. 6650 works perfectly with 6700 components.

Update to the origional question.
After spending better than 5 minutes on hold (on my $dime)with the shimano technical divisions long distance link, I'm going to re-post the question.
WILL the newer Ultegra 6700 series SS derailleur work with the older Ultegra 6600 brifters.
I asked this question of shimano and posed the question to the technical support people at Nashbar and Performance back last winter.
The response I got was: The brifters will work fine as there was no change to the brifters (6600 -6700)
NOW...apparently there has been(???)
I googled and got info that went in every direction with most saying the 6600 brifters shifting of the 6700 derailleurs was "B" at best.
LBS's wern't sure and were leaning toword replacing the entire setup (not gonna happen on my finances)
Question I have is this: Anyone have a link or online way of connecting with shimanos technical support so I can get a definitive answer (instead of speculation).
My intent had been to simply upgrade the derailleur and cassette to the 6700 series which would allow use of the 11-28 cassette and was a relatively inexpensive way to get a better hill climbing setup.
Shimano seems to be changing characteristics on its equipment faster than anyone needs and nothing is compatable with the former generation equipment.

The simple answer as already given, is that 67XX series will work with 66XX, however keeping groupset generations together will give better performance.

From use, have found that using the older series STI's work better with the new derailleur, than using older derailleur with new STI's, so what you are proposing should work fine.

Spoke (finally) with 'Anthony' at Shimano.
To put this to bed: The 6600 Brifters WILL work with the 6700 series SS rear derailleur.
They will NOT work with the 6700 series front derailleur as it reauires more throw than the 6600 brifters afford.
The 6700 series front derailleur IS required if one is going to utilize the new hollowtech 6700 series crankset.
Anthony said: There are folks who have installed the tiagra 12-30 and tweaked the 6700 series rear derailleur to work (and work quite well) with the 12-30 setup.
All of which answered the questions I had.
Thanks to all who offered their (valued) insights.