Have just done this – buying a part-ex off a developer.
Benefits are that it caps the chain, the developers are working on cash flow and want to get the property moved on, so a cheeky offer is always work it.
As mentioned above, it’s a “sold as seen”, so don’t expect everything to be perfect (we’ve a whole series of ugly rawplugs left in the walls, and some unpainted filler around one of the windows. Check what appliances are included before you make your offer and adjust appropriately. When we first viewed, the prior owners were still resident, they’d offered the range oven as an “extra”, which the developers didn’t take – so we had a 90cm gap to fill. Fortunately we’d factored that into our offer.
Dealing with the developers company was pretty smooth (Moving Made Easy), only niggle was not getting all the keys on completion day, they were at the new site sales office (about 200m walk) and the fun of completing on the day of the O2 network outage, confirming that we had completed so that we could get the keys and start unloading took a little longer than ideal.
And one other piece of advice. Don’t sneak an extra foot or so of back garden onto that land that “nobody owns”, and then build a summer house on it. Highways are way less flexible than a farmer might be when it comes to selling that small bit of land you taken from them. Like our original buyers did, which caused the chain to collapse.