I have acquired an HX. The HX Stomp looked very attractive due to its diminutive size, but the HX Effects won out as it looks like it will be easier to manage at a gig with the scribble strips etc. The idea being that I can treat it as two rows of pedals.
I plugged in my 4003 using a TRS => 2 × TS cable.
After a bit of a struggle getting familiar with the terminology and using the HX Edit app, I have managed to split the L & R inputs into two parallel chains so I can apply fx to each pickup individually, then the output of the two chains can either exit the machine individually via the L & R outputs if both sockets are used, or both chains are summed to mono if only the L socket is used.