My experience was that more power was needed using the SSB RX to reach an audio level on the downlink comparable to the normal FM-FM modes. A _very_ rough experimental number would be around 10-15 db more on the uplink. Still a very modest amount, but many were just not hitting it hard enough. By comparison, VE3NPC, WA8SME, and a couple of others sounded exactly as they do normally. My FM deviation is set from menu, and a deviation meter, so I don't touch it in FM modes. I had to slap myself alongside the head on SSB-FM to remind myself to turn it up.
No question that this is a trickier mode to operate. As you know, you need to think outside the FM-FM box a bit. Hi Hi!