Contractor with Perm Offer… Take or Switch?

I’m currently an inside IR35 contractor in Financial Risk within a top IB with a day rate that typically gets me £175k gross per year - have been earning this in the same role for close to 3 years now.

The team has gone through re-organisation, and the they have mentioned that I am a key man risk due to the knowledge I have accumulated, and want to convert me to perm (VP… so not Director level) with the base salary at 120k with expectations of a 20% bonus. With the benefits and pension match, I’m looking at around a £1,500 net pay reduction each month.

I’m really finding it difficult to make a decision. On one hand it’s job security and a redundancy package should that arise, but on the other, I am confident in my skills and output, and I can easily build the “redundancy” pot with the extra income.

Similarly, I’m wondering if my earning potential is mostly topping out in IB (pre-MD level), and wonder if there are other industries/companies that might be a good switch with a good WLB.

Was happy to stay contracting, but wonder if the market is dying and I should stay put…