All pond solutions are a great shout. I've recently purchased 2 of their filters for my 240L. I snapped a part whilst setting one of them up, which they replaced very quickly and for no extra cost after I emailed them. Although, not entirely sure, I would say it wouldnt be too hard sourcing extra parts if you were to email them. They were extremely helpful and showed a willingness to answer any other questions I had.
In terms of filter media I'm sure you could use other meida instead/as well as from the APS one, however I haven't bothered as you get the APS filter media included with the filter (bio-balls, ceramic rings, and carbon as well as some sponges).
Plus, for the few days that my filter has been opeational I am very pleased with the product. Nice quiet filter at a fraction of the price of some of the other externals on the market.
I wouldnt hesitate to use them again, and I know many others on this site have posted positive comments regarding this "up and coming" brand.