Clive I bought it aeons ago. With stock CFS3then it had something to offer, now I'm not sure.
It had then some big model problems. It offered BIX and a FBXIX, but the modelling was very flawed. The FBXIX had a bomber cockpit and Tsetse exterior hybrid. This I managed to get fixed. It is a fast Mossie, otherwise not different to the FBVI, historically there was not a FB XIX, but there was a NFXIX which had the thimble radome. Similarly, the BIX should have the bulged bomb bay, but looks like a BIV. But It offered an option to 'enhance' the FM and damage models, making them supposely faster and tougher than stock. Also altered stock flak so it limited the low angle of firing (that's a good idea eh! lol) There were hundreds of missions and a couple of campaigns. I can't remember it all and I don't know if they've updated it since. I do remember the handling of the aircraft was much better than stock and zippier than Avhistory v2 FM, but the V4 is the best FM for me.
If you interested I still have disc, which you are welcome to.
Edit: I've just found the models in my archive CFS3 folder, and they are not externally or internally different to the stock.