If all three R550 have dedicated Ethernet uplink to the switch and obtaining PoE, then mesh won't provide additional enhancement. If however one AP is running on DC power source and no Ethernet cable available, this AP could use the mesh feature to link back the other two APs having the Ethernet.
If your switch does not negotiated the full power, ie: only 802.3af then R550 will have limited performance due to power restriction from the switch, see below. If using Ruckus ICX switch, the PoE+ switch would always negotiate the optimal setting. In your case, you can try to logon to your switch (if is does, as you mentioned it is managed switch), fix the PoE port to 802.3at static output.