Thanks @Glos Guy.
When I ordered my current A1 the advance payment was around £560 but I added over £3k of options, so as you say the economics of the extension are slightly better. Also, personally it doesn’t bother me that with the extension I’m still paying the full PIP benefit as it just means the agreement carries on as it has been, which is fine for me.
Because the cars I’m interested all have significantly increased AP’s compared to when I last ordered, that’s the tough decision for me, especially when factoring in the inevitable options packs on top of the AP.
If I keep my current car until the end of the lease, it’ll be 5 years old so worst case scenario, if I lose PIP, the most likely option would probably be that I would lease a slightly newer used car, depending on the cost implications.