From the display, it looks functionally identical to the enclosure that I have, but with a different case design. However, my solution would cost ~£73 (£23 + £50) for 160GB storage vs £120 for the equivalent thing from cbadigital.
£64 for a 40GB solution that is otherwise the same thing seems a pretty poor deal. You could always bring down the cost of "my" solution by fitting a smaller HDD.
Personally I'd spend £73 to get 160GB. I use mine not only to back up memory cards in the field, but also to backup all my photos, software and documents from my laptop. I still have spare capacity, for now, to safely download all photos from a wedding or travel vacation etc., when out and about. A 40GB solution would severely limit its use and I'd rather spend the extra £9 to have far more capacity and flexibility.