Hey... to help a fellow brother out (jb)... i will copy three posts from other boards. Two I made and one Steve made, OK?
1) If you V-TUNE....., the CLB effects all areas of the tune... the O2s are 'reporting' 14.6 when in fact it is like (Say for example) 14.45, because of the offset. During v-tune when everything is set to 14.6... the offset is really 14.45, so as the ECM learns the VEs, those VEs are actually learning at 14.45 all across the board, even tho you told it that what it was seeing was 14.6. See?
It's that .15 AFR that is 'off' in all areas. So... 13.9 in the AFR tables is actually 13.75. It's not that simple because that offset will be in the VEs and not in the AFR table itself. But one COULD adjust their AFR tables, which are NOT closed loop, downwards that .15 AFR to be 'spot on' if they so desired.
If tuned with conventional methods (NOT V-Tune) then the AFRs are spot on regardless of the CLB, because the VEs were inputted by hand using other methods to determine the VEs and AFRs.... like using wide bands on a dyno, or a sniffer, etc.
I don't think .2 AFR (or less) RICHER will really effect anything at 13.1, 12.9, etc.

2)I think what most miss, but lonewolf brings up is this: AFTER a v-tune... the cells that are marked 14.6 are in closed loop and those cells are using the CLB in figuring out what needs to be done to keep em in order, right?
What is forgotten is this: during a V-Tune, one has that CLB set to something different that 14.6 which means the VEs will be slightly fat because the ECM THINKS the O2s are reporting 14.6 instead of the 14.4 or whatever the CLB changes things too. So... all the open loop cells, if tuned with v-tune, will be slightly rich. Not rich enough to matter for the most part, but rich nonetheless. One can see this using a Twin Scan AFTER a v-tune. I feel it is good because FAT really never hurt a thing, but lean sure can.
Another thing to keep in mind, if newer at this is: the 'cells' we see in TTS, etc. really do NOT exist as such. The 'cells' are just a way to change the machine language in the ECM into a GUI that WE, as humans, can understand. What that means in all practicality is that each cell we fool with interacts with each cell that touches that cell. Thats why Steve likes us to have everything kinda smooth.

3) Steves post.... "
The CLB's only effect Closed Loop BUT what the ECM learns in closed loop it applies to open loop. So any offset you place in the CLB will show up in open loop as well as closed loop if you use Vtune for tuning."
Hope that helps somewhat Bro.