I had exactly this dilemma before i bought my IS300h, but when i drove both back to back the decision was easy for me.
There are no known issues with the hybrid drivetrain generally, but you're correct to worry that in many years to come the battery may need to be replaced. The F-Sport has quite a few styling differences between the other models, including F-Sport wheels, LFA Inspired dash, sports seats, etc.
Also you may want to consider if the IS300h has less road tax in your country compared to the IS250, due to lower CO2 emissions, because this can significantly contribute to lower running costs.