Chris,
I have both an APTC SP chuck and a record power RP4000 chuck. In my opinion the APTC SP chuck is the leader of the field for the following reasons:
1) I cannot think of a work holding situation that there are not a set of jaws available to deal with.
2) It's build quality is excellent (However, see note below)
3) It is future proof - If you get a new lathe, just buy a new backplate.
4) You can buy additional jaw carriers (you cannot with the record and if you change jaws often it is a real pain to keep unbolting the little allen screws (this problem is worse still if you make you own jaws and have to align then each time - bowl reversing cole jaws for example)
5) The deal they have at the moment is fantastic (although I am not really sure of the use of the external / internal jaw sets but they are thrown in so what the hell!)
So, what are the down sides?
1) COST! It is the most expensive and if you decide to get a set of jaw carriers for each set of additional jaws you buy then the cost will add up.
2) Size - it is a large & heavy chuck. OK if you have a reasonable size lathe but it may be a bit big for the small lather (I have an Axminster M900 and it is about as small a lathe as I would use one on - weight / distance away from headstock vs machine bearings considerations etc).
3) I said in (2) above the build quality is excellent (which it is). However, I too bought my SP chuck on the deal you are looking at when it was first launched approx 18 mths ago. I had to return the first chuck as the action was very stiff. Apparently there are two sources of these chucks both made for axminster to (I am told) the same standards and tolerances. The ones sold as individual items for full price in the cataloge are Romanian, the ones sold as the kit are Chinese. However, when I took my first chick back for exchange I was told that all the future chucks, both sold as part of the kit and individually would be the Chinese one I was exchanging. Was my first chuck a rogue bad one? I am not sure, all I know is that the one I exchanged it for is A1, there was no bother in getting the exchange and I am v.happy.
4) I had to do a little draw-filing before I used it to remove the rough edges. 10 mins work but should it not be already done on the top of the range item
5) It is not coated / plated. This leaves it open to surface corrosion where as the record chuck IS plated and will always be shiny.
So, with £149 to spend on one one chuck which would I buy, I think I would have the APTC SP unit.
Hope this helps, PM me with your number and I will give you a bell if you want to have a chat about it.
Simon