I love my Pure Pro, but I regret that the bunch of non-standard keys makes it nearly impossible to replace keycaps with a homogenous set, even when using caps from a set of 104/105 blanks. So I'm thinking about making my own layout with more standard keys while retaining the arrow cluster in the bottom right hand corner (which I use a lot, often in conjunction with the right Alt modifier, which was the reason i got a Pure Pro).
Here what it could look like:

The only non-standard key would be the 1 unit Fn key, but that would be a minor problem compared to the current situation. The arrow cluster can be adjusted so as to allow any 1.25 modifier to be used as a Fn key:

With this layout, the biggest tradeoff is the lack of a right Shift key; I am not sure yet how much I'll miss it. The only modifier on the right of the spacebar I need is the right Alt (AltGr in french); I can live without the right Windows, App & Ctrl keys, which I've not used for years.
Also, I've ditched the CapsLock key and replaced it with the left Fn, which replicates the setup on my Pure Pro, which works very well for me.
So, do you have any suggestion? I'll remove the right Shift cap from my keyboard to see how I can live without this key, but in the meantime, I'm interested to hear if you have better ideas for the bottom right hand corner.
Also, since I want the largest possible compatibility with keycaps sets, is the 6.25 units space bar the best choice, and do you think I should go for an ANSI layout instead of ISO?