Any benefit in range when using a Class 1 BT emitter with a Class 2 receiver?

Hello,

A pure Class 2 emitter/receiver connection has a too short range for my project (I need 15/20m). So I plan to use a Class I emitter. However the receiver will still belong to Class 2. Shall I have an extended range with such a configuration (even if it's not as extended as a pure Class1 to Class1 connection)?

Thank you in advance.

Bluetooth needs data to go both directions. If the class 1 can't hear the class 2 then they won't communicate.

Look up "reciprocity theory". That says that if antenna B can hear antenna A, then antenna A can hear antenna B when they both have the same input power. Those two antennas can be totally different sizes and configurations. So you can put a big antenna on the base station to improve reception, which also helps the small antenna on the mobile unit receive.