Many 2 bay NAS cost close to that figure, so it's still convenient, and more bays are never enough.
The only two problems with the Helios, which I monitor since last year, is that it appears to be not 100% stable yet, although most problems reported in the forums seem related to excessive clock speed (which can be throttled down), and being always out of stock. It's a revolutionary product given the price and features (how many noticed it also has a small UPS on board?), therefore as soon as a new production batch is ready it goes away almost immediately.
I think the 4 Bay Size ( The 4S ) fits me better. I just prefer something taller wider than taking lots of ground space. I dont have the luxury to live in a large flat. Although the 4S is now discontinued?
I dont quite understand "excessive cloud speed". Assuming I am only using it for file transfer and nothing more would it still be a problem? Or is it something to do with Filesystem. I haven't checked out if the default support something like ZFS or BTRFS.