Just spoke to Emmanuel. First of all, there is no price difference between the standard products and the hotrod versions. This is because internally both the standard versions and the hotrod versions are essentially identical. That is all parts are installed, regardless of the version. In hotrod products though only a single input and two outputs are available.
Furthermore, the input selector, tape loop, and mute button circuitry is bypassed and disconnected.
This means that if a customer later decides to convert a hotrodded device to standard configuration, this can be performed at minimal cost. This also makes the resale of hotrodded devices much easier.
Emmanuel said that the convenience of extra inputs, selectors, mute, etc. . . are tradeoffs agains musical purity. The sound of hotrod devices is in his opinion slightly superior to standard configuration First Sound preamps.