I may be wrong, but I get the impression that Murray is looking to cut costs. If so, using sodium thiosulfate isn't a good solution -- at least, not unless you can find a source that's much cheaper than those I've found. Based on my cost data (mail order sources including Photographer's Formulary, Art Craft, and The Chemistry Store), a typical sodium thiosulfate fixer costs about $2.00 to $2.50 per liter, most of that in the sodium thiosulfate. The Agfa 304 formula mentioned earlier is $3.04/liter. Ammonium thiosulfate fixers cost about half that. For instance, TF-3 is $0.90/liter, once it's diluted for use.
Of course, all of this is based on the assumptions in my costs spreadsheet, such as the quantities being purchased and shipping costs. The most important of these costs are $5.10/liter for 60% ammonium thiosulfate from Art Craft and $13.40/kg for sodium thiosulfate from The Chemistry Store. Both prices include shipping. This analysis also assumes similar capacities from the two types of fixers.