The previous Volvo S40 and V50 were basically Focus underneath, but the V40 - especially the newest ones - have Volvo's own engines.

Inevitably you're going to take a hit if you sell any car in its first year - I'd say it's only worthwhile if for whatever reason you really don't like your Focus. If that's the case, get a good long test drive in a V40 - there's now a better choice of petrol engines - and make sure you prefer it.