I haven't observed any power creep.
Amazing, really, that there hasn't been. I've argued elsewhere that the newer units from D1 - D3 are competitive and interesting and I stand by that remark.
But compare Rise of the Valkyrie & the units from that magic box: Airborne Elite, Raelin, Grimnak, Krav Maga Agents, Marro Warriors and Sgt. Drake all continue to have tournament relevance even today, and the others - Finn, Mimring, Carr - are borderline candidates who make frequent appearances in our casual games.
Power creep? No, I don't think so. The Dx units have been relevant, interesting, and balanced.
I have *aesthetic* issues with some of them, but that's not what you asked.
