I'm still vacillating over dedicated arrow keys vs putting them in the Fn layer. I've been experimenting through my workday by switching among my IBM SSK, Poker II, Keycool 84, and Leopold FC660M.
Whereas I can do everything with the Leopold and Keycool that I do with the IBM, when I am using the Poker II, I am finding it cumbersome to navigate in documents or molecular modeling programs without dedicated arrow keys. For straight typing that does not involve any navigation or complicated editing, the Poker II is fine, but for even slightly more complex work, I prefer the Leopold, Keycool, or the IBM.
Between the Keycool and Leopold, I prefer the look and build quality of the Leopold. I also do not need dedicated F-keys, so again the Leopold wins.
The key action does not feel as even or precise across the board with the Leopold as it does with the IBM, and so between these two, I am more comfortable typing on the IBM.
If I had to leave the IBM out of the equation and consider only the Poker II, Keycool 84, and Leopold FC660M, although each board has its strengths, the main thing is getting the work done, in which case the Leopold wins. The Leopold is not strictly a 60% board -- it adds a little over 1.5x key units to the width of the board in order to accommodate the arrow cluster without unduly squeezing the right shift key or changing the staggering of the z-row. Attempting to include dedicated arrow keys within a 60% format necessarily results in a non-standard layout, and putting the arrow keys in the Fn layer adds a layer of complexity to relatively common keyboarding tasks.