2012 Stamp Duty provisions

My client is a property developer and acquired a uk ltd company in 2010 which owned a property in need of development. He has now nearly completed the work on the property and is looking to market it soon. It is comprised of 3 flats and he is open to the idea of selling each flat separately or if the right offer comes along to sell the whole property. It would be simpler for him to sell the company in the latter case but what is the Stamp Duty position for the purchaser in that case bearing in mind FA 2012 and the recent cases (one won and one lost by HMRC)? The sale prices will fall into the 15% SDLT level whether it is one flat or all three. My client is concerned that if it proves to be 15% he will need to adjust his sale price expectations accordingly. Any other ideas e.g if separate flats he could create leaseholds.