As Skejcior said, the private dummy is 10% more efficient than Public ones but can only be used by 1 person at a time.
Just want to point out that this is specially important during 2x skill events. During those events the Private dummy becomes even better!
Here is how it works, let's say that a public dummy has a 100% efficiency on a normal day:
- Public Dummy, normal day: 100% efficiency
- Private Dummy, normal day: 110% efficiency
- Public Dummy, 2x skill event: 200% efficiency
- Private Dummy, 2x skill event: 220% efficiency
That's a considerable difference!!
Every 5 weapons you use during 2x skill event, is as if you "won" a free weapon on normal days.
Considering 1 weapon costs 20 TC and 1 dummy costs 900 TC, you would need to "win" 900/20 = 45 Weapons to payoff the dummy investment.
This means that if you use 225 Weapons (45*5) on double skill days, you have already covered your losses of buying a Private Dummy.
On normal days, you would have to use 450 Weapons to cover the Dummy cost, tho.