In the extra keys store section it states the following: “It’s a tight fit with a 1.5U key; you could use a 1.25U key instead…”. What does that actually mean, does the keys bind with the 1.5U option? Could it affect the keyboard long term? What are the actual drawbacks of using the 1.5U key?
Thank you very much and have a great day.
You can choose either 1.25U or 1.5U. Either choice will work with the smaller space bar. See this example photo with the 1.5U key and JIS key set:
Just be careful and note that you may need to burnish the bottom left edge of the 1.5U key a bit just in case you think it is too close.