The 3yr GFV at 4000 miles per year when these crazy deals were on in Sept 2017 was around the £6430 mark then dropped to £5500 ish by spring 2018 remaining at about that level today. So it seems the decision to hand back or sell, from a purely financial perspective, may depend on any excess mileage and when you bought it, with the higher GFV resulting in a negative equity scenario. I really cannot see 3 yr old bikes in Sept 2020 being worth around £6500 trade for a dealer to then sell for a competitive price and make a reasonable profit, just won't work for them. They will offer significantly below the £6500 GFV or over allow it's value in part exchange, hence removing some of the discount on the new one that you could negotiate if you did not part exchange.
If however your GFV is nearly £1000 less you could make a slight profit or at least break even. Deciding to keep and buy means a well priced bike that you know well from new which in my view is worth paying for.
Having said all that, regardless of the GFV, your monthly payments will have been adjusted to tale account of the difference in the GFVs, deposit paid and mileage. At the end if the day you will own the bike for around £8500-9500 depending on the deal struck on purchase, the same figure as if you had bought it for cash due to the 0% interest rate. You may also have been able to make that cash work for you of buy another bike, happy days.
If however your GFV is nearly £1000 less you could make a slight profit or at least break even. Deciding to keep and buy means a well priced bike that you know well from new which in my view is worth paying for.
Having said all that, regardless of the GFV, your monthly payments will have been adjusted to tale account of the difference in the GFVs, deposit paid and mileage. At the end if the day you will own the bike for around £8500-9500 depending on the deal struck on purchase, the same figure as if you had bought it for cash due to the 0% interest rate. You may also have been able to make that cash work for you of buy another bike, happy days.