The Futaba S3016 would work in place of either one. It's slightly smaller than the 225 and slightly larger than the 85. As far as power goes, it's 7 ozin lower than the 225 but 5 ozin higher than the 85, both at 4.8 volts. Since all three can operate at 6 volts, you can get a bit more power out of them at that level. Don't know anything about Savox