It's not my era anymore (with more than a little bit of sadness) - but Pat makes some good points, I think. I've looked at the pics of the sets in question and the Australians do look just a bit more natural in the pics.
They look very good but I second the suggestion for the Arditi to have at least one pose wielding a knife and perhaps another bomber or two, they used plenty of bombs and knifes. Their pose look a bit too static. As for the infantry have you considered to make all figures headless with a separate sprue with 1915 cap, adrian helmet, adrian helmet with bersaglieri plume and alpini cap heads? So the figures could be customized for all the war. For 1915 you trim the gasmask box and insert the cap. For 1916-17 use as the adrian helmet. For 1918, ideally, you should again trim the gasmask box and add the british gasmask pack on the chest, but this latter point would need another sprue and it's perhaps too much work on some figures.
Easy enough to convert a few with knives from at least two of those figures, though as always more is better, perhaps add an extra arm with knife for the grenade thrower to replace the rifle(or remove it and add a knife at the digital stage) though logic dictates a grenade thrower should have his off-hand free to prime the grenade... and add an extra Arditi head to convert an extra figure etc...
The biggest problem is perhaps no early Italians, which I think would require another set, otherwise its basically conversions alround though other then heads with kepis and no gas mask cases there not much to change, I think this could be done digitally using the current scans from the heavy weapons mortar man( wearing ordinary soldiers kepi) and officer figures...
These guys look great. I also like the idea of arditi with close combat weapons, but I prefer to do my own conversions, which means that these are great for me. For sizing they should match up to Hat WW1 Germans (not the airfix reissues) and WW1 Austrians. Nicely done, Hat, i look forward to these.
Please do not that ALPINI's cap, because it's the worst I've ever seen. It is like a Messican Bandit rather then an Italian Alpino, 1st there is no black feather: even in battle no Alpino would be without it 2nd the "crown" of the hat is too tall 3rd the the brim: it must be in the front as wide as the head or little more, and more bended near the head on the rear and on the sides. I hope to be usefull to your good project. I hope you will do the best sculpture of Apini Arditi
The knives appeared a lot but just in posed pictures. In real action it was used only in the cutting trench moment. Handguns were very usefull. The poses are amazing. Maybe the fez hat are a bit too much as out of statistics. The hats without feathers are ok if the figures are used as "arditi del popolo", ex soldiers and one of the first opponents of the early fascists, during the 20s. In my opinion, the whole set can be used for good representations of the "biennio rosso" civil fights on different sides, armed civilians too.