I agree with raspi.
With ebtables we could give our user transparent caching system that could give better internet experiences to user.
Using distributed web caching using zeroshell, configure as sibling could increase web browsing performance. With web caching, bandwidth saving could reach 20%.
Also, the “caching box” can not see by client because using bridge mode.
The security and QoS could be implementing in the bridge mode without add higher latency from layer 3 applications.