Also pip is paid 4 weekly and not monthly, from 01/04 at £80 per week, £4160 annually, so actually works out at £346.67 per month.
You then also need to factor in the pip rate rises in 2027 and 2028, was over 3.8% this year.
When you add in the £6499 AP, the salary sacrifice will be substantially cheaper over the 3 years.
Obviously would need to factor in the reduced pension contributions and see how that would affect things longer term.