Sure, I thought about what you said so I went and checked the digit height on the tubes. The come out at just under 3/4" at 18mm. The 16 segment displays I'm looking at come in 3/4" and 1/2". I was thinking matching the sizes would of been perfect. Sketching it out it looks 1/4" under is fine and will keep the tubes more prominent which is great. Also, the 1/2" are available in CC (although in packs of 19)! So back to the HT16K33.
Cant find any suitable 14 segment. Yes in no rush for it so price point is important to get right, I'm no stranger to Chinesium parts when appropriate, unfortunately.
Could you recommend a starter breadboard project with Arduino and the HT16K33 to get me going?