I have noticed that there seems to be a bug in the display of the currency symbol in the cart in VM 2.6.10. To see it
add product to the cart
view the cart
change the currency using the currency selector module.
You should see that the currency symbol does not change, although the calculated prices do seem to be converted correctly. If you select the same currency again, this time the symbol changes to the correct currency. If you try to go back to the original currency, again you have to select it twice before the correct symbol displays. It is quite confusing and does not look good to the customer.
You seem to have fixed this issue in VM 2.9 - it would be helpful if you could publish what the fix is, I did do a search and could not find anything on it, but might have missed it.