Batteries For Flashes. 1.5v versus 1.2v conundrum ?

Most standard alkaline batteries come in a 1.5v flavor. Rechargeable batteries are mostly 1.2v. I think most flashes are also rated 4x1.5v batteries as are most electronic devices in general. Even my desk phone needs 1.5v x 3 batteries to run properly.
For most of us using rechargeable batteries will this cause under-performance or would it even be bad for the flash. The 1.5v batteries might perform better in terms of flash recycle ? I work with NIMH batteries and they are all 1.2v. They are 1.2v everywhere and Ive never seen them in a 1.5v version. My Nimh batteries perform kind of ok. I recently bought panasonic eneloop pros and even that struggles to keep up my desk phone running. So I'm wondering how efficient they will be in my flash sincethey are all .3v lesser than required.
Ive found 1.5v alkaline rechargeable batteries for sale online. Has anyone worked with these and how do they perform. Could anyone tell me if its possible to use my smart NIMH charger with auto cut-off to charge rechargeable alkalines ? Or do we need a specific type of charger for rechargeable alkalines ?
For most of us using rechargeable batteries will this cause under-performance or would it even be bad for the flash. The 1.5v batteries might perform better in terms of flash recycle ? I work with NIMH batteries and they are all 1.2v. They are 1.2v everywhere and Ive never seen them in a 1.5v version. My Nimh batteries perform kind of ok. I recently bought panasonic eneloop pros and even that struggles to keep up my desk phone running. So I'm wondering how efficient they will be in my flash sincethey are all .3v lesser than required.
Ive found 1.5v alkaline rechargeable batteries for sale online. Has anyone worked with these and how do they perform. Could anyone tell me if its possible to use my smart NIMH charger with auto cut-off to charge rechargeable alkalines ? Or do we need a specific type of charger for rechargeable alkalines ?