I am about ready to purchase another set of servos to get rid of the RJXs in my fleet (tired of having to re-initialize 2 - 3 times every flight - and yes I am running a 2S lipo).
I don't know much about the RJX servos, but it seems to me that you may be looking for servos that perform very well, but that are also efficient enough to work within the current limitations of your system.
I power the electronics on 5 helicopters with the BEC Pro with 6S input and 7.5V output. For cyclic servos, I use the Futaba BLS 255HV's and the MKS HBL 950HV's. For rudder, I use the Futaba BLS 256HV's and the MKS HBL 980HV's. I cannot get the system to brown-out at the bench with the
VBar Pitch Pump Test (VBar Silverline Pro, Pitch Pump 100, Tail Torque Precompensation for Collective 100, and Tail I gain 0) with any combination of cyclic and rudder servos in any of the helicopters. Interestingly, I can get the Align DS620/DS650 servos at 6V to brown-out the system with
VBar Pitch Pump Test. Also, unlike the annoying buzzing noise of the Align DS620/DS650 servos, these Futaba and MKS servos are Prius quiet.
Although both the Futaba and MKS servos perform excellently, I prefer the MKS whenever possible. The MKS have a sexier metal case, have
all metal gears, and are generally cheaper than Futaba. The MKS also have less slop than the Futaba's when tested by hand. However, the Futaba servos are shallower so they fit perfectly on the Synergy helis. The MKS are deeper, so generally need to shim the left and right cyclic servos to avoid butt-to-butt contact. Still, pilots claim no impact or detriment in head geometry from shimming the MKS servos.
Now that the Futaba 255/256HV servos are discontinued, and the 272-274SV have a substantially higher price tag, I don't know if the higher price tag is worth it for the average pilot.
I would be interested to learn if the BEC Pro with BK servos combination at 7.5V can survive the VBar Pitch Pump Test.