... Haven't tested for digging planting holes yet - I'm thinking a good shovel or a wide auger bit might be easier/cleaner, but I shall experimemt idc when it comes to digging lots of holes for transplants.
Verdict on Mantis v earth auger v shovel for digging multiple planting holes:
Mantis - quite good where soil already loose/fairly weed-free and not too many other plants close-by (which will get covered by the spoil and also hinder recovery of spread soil back into the planting hole!) Effort required to transport and restrain, while digging, is very bearable for quite a long while. Unfortunately, Mantis not good for starting holes in the very weedy ground I've been tackling recently. (Good for slimmers though: actually, I should get the Mantis out having had a relatively sedentary winter when I also stopped smoking resulting in a bit more snacking and a bit more body girth!!)
Single-person earth auger with 200mm auger bit - hard work "holding" auger while churning through well-established meadow grass. Once through the turf it's OK with my soft soil, but the combined weight of power-head and a double-helix auger-bit takes its toll with the the lift-and-shift between multiple holes. (Probably also good for slimmers, but likely to result in a new twisted body-shape after an acre or so
)
Hand digging with a good, sharp shovel/spade - all will know this is always hard work! But it's less stressful than either the auger or the Mantis. However, it is just so boring (mentally) when digging tens and tens of holes at a go and I have 1000+ to dig overall. (Obviously also good for slimmers!)
Summary: it's hard work no matter what option!
However, I think I'm going to give the auger an extended/preferential trial hoping that I will regain the necessary upper body-strength in reasonable time to make it less onerous!
In good, loose, open soil, I would be more tempted by the Mantis option despite the wider spread of the "diggings".
Hand digging is eco, but I just can't stand the boredom, especially when digging solo. (I was in such a foul mood recently after manual digging for 100x apple plantings.)