Existing system, new boiler

[Hobo128]

Need to price a job soon. It's a conventional system. I think it's a y plan, maybe s plan. Boiler that's in is a baxi solo.
The customers want the boiler changed but nothing else.
I have looked into the worcester Greensted ri, is this as simple as worcester claim. Is it a simple swap over job and wire up the old controls or is there more to it.

Thanks

 

[GasmanxxxR1]

Baxi solo is normally 3 wire so you may need to think about that, sometimes you might get lucky and find a 5 core there