My thoughts:-
4.9% APR is not unreasonable.
Low GFV doesn't give any protection against high depreciation, but I think M3 residuals will be strong anyway, so not a major worry.
PCP makes monthly cost less painful than HP, but obviously a little more expensive overall.
Should be a little equity in the car at the end of the term and could allow early trade in if you prefer (although Tesla trade-ins are generally poor value)
With a big deposit (like £15-20k) and 3 or 4 year term I will possibly take it over straight HP.
Only thing putting me off is the balloon payment at the end, which makes it more awkward to sell privately i.e. will have to pay it off first and then sell. I don't think simply handing it back will be a sensible option with such a low GFV as I think you would lose out significantly.