What's the largest bytes cached by ReadyBoost that someone can expect with a Windows 7 laptop with 8GB of RAM?
I adding a Class 10, 16GB SD Card, primarily for ReadyBoost, and I haven't seen the cache size go above 3.5GB (out of 12GB allocated).
My usage is 90% Chrome (with dozens of tabs), a bit of Office, text editors, and remote access apps.
If I can't realistically expect it to go over 4GB, I would reduce the space allocated to it, in case I need the space for random tasks (like moving a 10GB file via SD card sneaker net).
Update: After a few weeks of running this laptop, I have spotted ReadyBoost using over 7GB of cache file.