Thank you for sharing so much of your Pilot pen wisdom with me! I wonder if the plastic of the Custom Heritage 91 series is similar to that of the Prera? If so, I should like my pen a lot! I do like the CON-70 very much due to its ink capacity.
You are very welcome. 'Not sure I'd call it wisdom, though. LOL
I think the Custom 91 plastic is thicker and, of course, heavier than the Prera. The Prera is a pretty basic pen although it is well-made. It is, indeed, pretty. I have two, and they do the job. (I use my pens for journaling and drawing.)
Yes, the capacity of the CON-70 is excellent, considering it's a converter. The cool, Japanese magazine (actually a "mook"=magazine/book), Shumi-no Bungu Bako, did a comparison of converters and popular, current fountain pens, including dedicated piston-fillers. The CON-70 holds 1.10cc of ink and a CON-50 holds 0.81cc. According to the magazine, which I believe is trustworthy, a Pilot Custom 823 holds 1.59cc of ink (it's a big vacuum-filler), and a Montblanc 146 holds 1.37cc. Surprisingly, the 146 holds more ink than a Diplomat 149 which holds 1.32cc. Everybody seems to think a Pelikan M1000 holds a lot, but the article states that it holds only 1.20cc and an M400 actually holds 1.35cc!
The real surprises are in the form of cartridges like the Waterman which holds 1.30cc and an Aurora (Parker-style) cartridge holds 1.20cc. A typical Euro-style converter like a Montblanc holds 0.85cc of ink and the short, Euro/Montblanc cartridge holds the same amount! The Pilot (Pi-roh-toh) cartridge holds 0.89cc, Sailor (Say-rah) cartridge holds 0.84 and a Platinum (Pu-rah-tih-numu) holds 1.14cc of ink. BTW, the pronunciations are the Roman equivalent of Japanese Katakana and Hiragana, and I mean no disrespect. I lived in Japan, love the people, the country, the language, and the general passion for details and high-quality. Kung-fu (yes, I know, not Nihongo.)
Regarding ink capacity, I, actually, don't mind refilling. It's a meditative procedure, and I can daydream about the perfect, old-fashioned stationery store, run by Ozzie & Harriet, or Yoshi & Yumiko (whoever they are, they are "pensei," pen-sensei, more serene and knowledgeable than nibmeisters, but humble). The little shop is jam-packed with every imaginable writing instrument, stationery artifact and pen emphemera (no, you won't need imodium) from everywhere in the world. A stationery aleph. I almost found a place like that in Tohoku, Japan (I should have bought all the Myu mannen histsu). Anyway, I just like the vacuum-action of the CON-70.
(Roh-bah-toh in Japan)
No matter where you go, there you are.