London is as expensive as New York, where I'm moving. In fact, I will be paying roughly the same rent: $950 before bills in NYC, £850 including bills in London. In both cases I'm around 30 minutes from the city center.

My company is providing health insurance. I will be working the same hours. The biggest difference benefit-wise is that I get ten days less paid vacation (15 vs 25)--but I mostly used my vacation to visit New York.

A dev job in Indianapolis (or anywhere else between the coasts except Chicago) would pay what I make in London and the cost of living would be halved.