Check out what tomscy2000 had to say about Canalworks custom iems on page 138 of this thread:
I don't think the 1Plus2 has a similar midrange to the ER4. The TWFK sounds very different from the ED, IMHO, and the two will never sound similar in my book. I've actually done blind tests (same exact black shells) between the ED, TWFK, and GQ, and was able to differentiate the three. I was confused between an ED/CI combo vs. GQ, but that's understandable.
The CW-L05QD uses four Sonion 2354 in tandem. It's paired in sets of two, with dual bores (identical 680 ohm damping) and a voltage divider between the two sets of dual 2354. I think it's brilliant. It definitely gives off an ER4 vibe, but the soundstage sounds bigger, grander, airier.
CW also has the CW-L01, which is a 2354 with a 100 ohm resistor attached; sounds like the ER4S with slightly better bass extension (because of the bass venting). It also has a CW-L01P, which is a 2354 with less serial resistance, and sounds more like the ER4P.
Hayashi-san seems to be an admirer of the ER4 sound, and the majority of his models have modest levels of bass with present, bright-ish mids, but controlled sibilance. I'm a fan of his products.