It was the fact that I already had the HX FX to start with that stopped me, really. £400 gets me the Stomp vs £1200 or whatever it is for full Helix. I could obviously have then sold my FX but would still have been out of pocket.
Between the two units I should (I think) be able to divvy up the DSP enough to do anything that I would do with a full Helix (not saying its as powerful, just that it's as powerful as it needs to be for a fuckwit like me). The Powercab looks easy enough to just plug and play as well, which was appealing.