Shovel’s no sprint bonus isn’t that actually significant that Ogryn’s mobility is bad anyway unless you use Rumbler to dodge, even then, you can’t dodge like Combat blade Zealot.
(I only used Latrine shovel in Damnation difficulty because of that’s the only weapon that has proper blessing for my build now.)
I want to say the weakest melee is the Club in my opinion, it’s not because of mobility only. It has terrible attack speed and second heavy wind-up, even with my 72% finesse club, it’s slower than shovel. So it’s difficult to control horde.
I had difficult time with club when you are dealing with mass of enemies on your own in Heresy difficulty. (when you are surrounded, and you should deal with one side of horde) And elite killing per se, Zealot is way more faster to kill elites in melee (Maybe for Crusher club will be faster especially with heavy weight talent, but I am sure right blessing combination with Combat axe + ult Zealot is way more faster to kill Crusher), and most of all your Sharpshooter who carries Bolter kills elites, so Ogryn should do your teammates by staggering elites. I usually use Rumbler spam for that.
Shovel is kind of middle of Cleaver and Club now, almost same cleave like Club, but faster, you can actually damage (33% weaker?) to Crusher like Club unlike Cleaver.
And Club’s headshot technique is very inconsistent. It’s okay when your target is at your end of melee range, but when the target is closer, it’s hard to land headshot. I reported it as bug.