I have an older Pferd type guide, a Husky roller, a Stihl roller, a Timberline, a Gramn and a Homelite410 vice. I also have a grinder with a Dinasaw wheel. Clearly, I am a easy sell for any gizmo.
I also have a 'collection' of different filing guides, etc. But mine is because I am interested in trying different ones out, just for curiosity.
Most of these will sharpen chains adequately, if the user understands how they work, and what the finished cutter should look like. If they get that, they should be able to sharpen with any of them. Some have limits, like fixed angles that some users will not like, or only work with certain chains. Everyone needs to find something that works for them.
. . . could you explain why recommended wheels are narrower than recommended files?
Round chainsaw files are available in 1/4", 5/32", 11/64", 3/16", 13/64", 7/32", and 5/16" diameters, and in standard and smooth cut patterns.
Wheels for chain grinders are available in 1/8", 3/16", 1/4", and 5/16" thicknesses, and in a variety of grits (coarse to smooth).
While I have never received an authoritative answer, I have to speculate that the wheels could be made in any thickness or grit, but that the market demand does not support that. If you custom order a coated (ABN/CBN) wheel, you can get it in any thickness, grit, and edge profile you choose.
If you truly shape the edge of the wheel to a half-round profile, and 'grind as you file', then it would make sense that the wheel thickness should match the recommended file diameter. Some people grind cutters to a different profile than they file to, by using the side of the wheel. Some people grind the cutters to a rough shape, and finish with a file of the 'correct' diameter. I assume that most people just use the recommended grinding wheel size, even though it is different than the recommended file diameter.
And how do these Aussie guides compare to the Stihl?
I have not used either of the STIHL roller guides personally (yet!). It appears that the FF1 (left photo) works with the standard (flat) STIHL file guides to maintain a consistent top plate angle and down angle (the standard file holders provide a consistent file depth, and a let you 'eyeball' the other angles). The FG4 (right photo) appears to fix the file in all three, main settings (top plate angle, file depth, down angle). These file guides may also work with skip tooth chain (if they set on the tie straps, rather than on adjacent cutters).
The Fast-Filer guides also allow the user to also set a consistent cutter length, by use of the vertical rollers. The Fast-Filer also claims to allow the user to set the depth gauge height.
Philbert