Some further follow-up:
(1) I mentioned in my review that I had managed to crack the back of the grip section by significantly overtightening the converter, and that Kevin from FPR had sent me a replacement. Given the congested nature of the postal system right now, it took a while for the replacement to reach me - and when it did, I had a problem: it took an enormous amount of effort to ram the nib and feed into the section, and even then I wasn't sure I had it seated far enough in.
I emailed Kevin to ask his advice, and was told that my best bet was to heat set the feed and nib into the grip section - and yes, that did mean heating the section itself (plus the feed) in near-boiling water, then inserting the nib and feed into the section. They do this for every pen before it heads out the door. I was assured this wouldn't cause the acrylic to melt, and I can confirm that this was the case for my new vermilion section.
I mention this because I think it's important for users to know, this is not as easy a pen to tinker with as the #5.5 Himalayas (where the nib and feed can be removed and re-seated pretty easily). With the V2 pen, you have two options upon removing the nib and feed. The first is to work out the orientation of the previous "set" of the section (the centre hole will no longer be perfectly circular, it'll be a little bit flatter where the nib sits - honestly, I found it a little hard to tell!). The second is to re-heat set the whole thing, which isn't hard (I had my first go this morning), but takes a bit more time and effort.
[I asked Kevin if he was willing to sell me a replacement grip section for my original #6 Himalaya, so I could convert it to a V2 with gold trim - he kindly complied, but suggested I retain the shorter feed in the section. I plan to do some more fiddling with this pen too, then provide feedback.]
(2) For anyone interested, I cleaned out the pigment ink from my Jade Smoke V2 Himalaya, and replaced with Blackstone Black Stump (an inoffensive grey/black ink with purple undertones). It's now writing much more reliably, and the railroading evident in the handwriting samples above is no longer an issue.
I still recommend these pens as a better option (for me) than the #5.5s - but if you like repeatedly swapping nibs around (as I do!), you need to be aware it's not as straightforward with the new pens as with the original.