The potential disadvantage is that you can’t charge for your services as a CRI.
Only if the CRI is a PPL and not a CPL, just the same as a PPL FI.
If the NPA on re-numerated flight training for PPL Instructors goes through then that will change as well.
LAA Coaches are all CRI qualified.
Many of us are also FI's and Flight Examiners.......