Alpasty I don't want to complicate your decision, but I had exactly the same question last year. I had decided, or rather become somewhat fixated on wanting an Axminster chuck, but just couldn't decide which one. I emailed their sales people with some questions, but our communications didn't go too well.
As a result, I decided to consider my options. After some research I decided to go for Vicmarc and for not too much more than the price of the Sk114 I got both the Vicmarc VM100 and the VM120 with standard jaws.
I like Axminster products but I have no experience of their chucks. I am sure they are perfectly fine. However, I am glad I decided to go for the Vicmarc chucks and wouldn't change them, they do everything I need. Its ideal having both chucks but I do tend to use the larger VM120 most of the time even for smaller work. I have also used it to turn large 50cm+ bowls and platters using blanks that weighed in at over at 30kg. I can't fault these chucks.
I don't know the weight of the Axminster chucks, my VM100 is 2kg and my VM120 is 4kg. I wonder if there is a similar difference in the weights of the Axminster chucks. If there is, I would suggest you go with the SK100 for your 1hp machine. If you're not cutting your own blanks you probably won't be using the full 35cm capability of your lathe too often and the 100mm chuck should be fine.
Whichever you choose I'm sure you will be happy with it.