Two years ago I bought a nice graphite casting rod for a new curado reel. The rod had micro guides. I figured the reasoning was just to reduce weight. Little did I know!
Recently I found a spinning rod with small guides after a few regular sized ones closer to the reel. This time I wondered what is going on? Wouldn't the smaller guides cause issues with a spinning rod?
Did some digging. Incorrectly sized guides cause line slap against the rod blank. There are a few other things that happen like extra friction which hinders long casts. The reading suggests even hook set and "feel" can be enhanced by proper guide size and placement.
The only detractor is if icing could occur or the passage of a knot.
Florocarbon line is considered the worst when used with a spinning reel. FUJI did some serious research and while they don't offer their own line of rods (that I could find) they have a calculator for which guides and the spacing.
IMO this is a very interesting video explaining the newer small guides:
https://www.youtube.com/watch?v=MDJiVBIC3Q0
