Hi,
i happen to work at Lindt & Sprüngli, hence I can give you some "first hand" info
Lindt factory outlet:
I beleive you will get the best deal in the Factory Outlet in CH, open from 10 am to 5 pm, Monday to Friday.
Bulk Chocolates:
some pralines are sold in bulk, and you can also find products in the assortment on bargain price due to:
- recipe changes
- package material problems etc.
Otherwise you can buy all the product in the outlet that you normally have in Switzerland. These are the real deals in the store (e.g 1 CHF/ 100g tablet...

)
Discount:
do not expect any further discount even if you buy 20 kgs.
Seasonal store:
During seasons (XMAS and Easter) there is an additional store for seasonal items. The xmas one is going to open on the 9th of November, and it is open on the last 3-4 Saturdays before XMAS as well.
Factory visit:
the factory is not open to public, factory visit is not possible.
cheers,