I use both base shaper and an organizer, all purchased from PurseBling. Doesn't add much weight and the structure of the bag looks great, and it's so nice to be able to find things in a split second!I have a Speedy 35 and use both. I purchased all my base shapers from eBay, dr.baseshaper is the seller I purchase from.
I'm a fan of Divide and Conquer too! She makes an insert that is designed specifically for the Speedy. It has a clear plastic insert in the bottom that can be removed if you find it's too stiff.I have a 25 and love my organizer from Etsy shop Divide and Conquer. It also serves as a shaper.
I used a base shaper for my Speedy. And when I went to LV my SA recommended to leave it out as it will hurt the corners eventually. At that time I had the base shaper for a couple of weeks and nothing had happened to the corners. However, I immediately removed it. For organization I use pouches and it works great for me.I would just use an organizer. Some members on here have expressed concern that a base shaper can hurt the corners of the bag.