When does the 15% off introductory sale end?
If kind of goes on a while. If someday you don't see it, just email or call and ask for it anyway. You might be pleasantly surprised.
If the past is any indication, it will be at least until after the free download of the L6 engine in February Logos knows many people will not purchase the upgrade until they have had a chance to "kick the tires".
Were the discounts on base-packages better the very first day Logos 6/Verbum 6 was launced, which was Monday last week?
Not technically, though perhaps in a de facto way. I couldn't get on the website at all that Monday, so I never got to even see an "initial" price. I think that was true for most, so that probably means that if you wanted L6, you were calling in. It would not surprise me if you were able to get a better deal than what's shown on the website by getting the right salesperson at the right time. However, I do not think that prices have [intentionally] changed that they offer through the website.
The website seems to show the same prices.
It has been noted elsewhere that Faithlife often has a 15% Limited Time discount on base packages quite a bit throughout the year.
I don't know how accurate it is but I have heard most of those recurring sales are for new purchases and do not apply to upgrades.
Thats true, they offered the introductory pricing to upgrades within base package families only twice. The rest of the time the offers were only available to people purchasing new, or upgrading to L5 for the first time. If you already had an L5 package you were out of luck.