Hey ootchia
I've got a detolf and although I can't comment on its suitability for syrians, I can say that Cadmium was very happy in it and Carbon doesn't seem to have any complaints either. Glass sides mean that you can add plenty of substrate (for a dwarf at least) if your hamster is a digger, I've found it very easy to clean and the open top has provided easy access to all parts of the cage as well as giving you space to minimise the "death from above" issue you can have with top-opening cages.
As far as cons, you would need to build a lid to prevent ecapes, regardless of the species of hamster you get, and it is a long, narrow space that could theoretically limit some of the enrichment you could put in there, though neither of these were an issue for me - building the lid was a learning experience! As cypher said, you would need a shallow end to fit the wheel in (unless you did something really complicated with the lid to make it taller, I suppose?) and I initially had some issues with Cadmium chewing on the metal frame when she was a baby (we think an attempt to clear space to extend her burrow?) but that was stopped with a temporary cardboard shield where the chewing was happening and she stopped doing it as she got older. Carbon hasn't shown any interest in chewing the frame so far, so that could have been a Cadmium thing, rather than an issue with the cage.
As far as food goes, all three of my hamsters were really happy with their respective Rodipet seed mixes, so if that's an option I would recommend that. They also sell a millet trio which you could try for additional forage options.
In terms of Pets at Home, I don't know if there's anything that you can't get anywhere else, but if you're there, they sell bendy bridges, seagrass mats and tunnels (i think it's seagrass) and grass nests which have all been popular with mine, and you can sometimes get Rosewood's peck n fly or harvest festival (
https://www.amazon.co.uk/gp/product/...?ie=UTF8&psc=1 ) which offers some foraging options. Both of those have flax sprays which was my main reason for buying them as all 3 of my hamsters seem to like flax sprays, though Carbon seems more of a millet boy. I also get mealworms from pets at home.
Hope at least some of this is useful. I'm not claiming to be an expert and would happily accept correction from other members, but this has been my experience so far