I can see two ways of thinking about this...
I currently have the WMD SSF ADSRVCA which I'm really liking, is this a good enough reason to buy more of them or is it better / more interesting with varied possibilities to buy things like the Befaco ADSR, Instruo Ceis, Intelegel Dual ADSR, Qu-bit Contour etc etc??? (Think exactly the same question for VCAs)
For the Befaco I'll probably do the DIY, Instruo looks pretty similar to the befaco then there is the Intellijel Dual ADSR which I really like the idea of as its based around the SH101, I used to own the Roland MC202.
I don't really have intentions to ever own a wall of Synth so maybe sticking with the WMD SSF ADSRVCA is the way to go, I'm also interested in something with a long cycle time.
Enjoy your spare HP, don't rush to fill every last space, this is not like filling sticker books. Resist the urge to 'complete' your rack, its never complete so just relax.