I know this has probably been answered, but what is the advantage of micro guides.

weight reduction, and thus sensitivity.

I've not personally felt a good deal of improvement casting with casting rods and micro guides, but it seems to help on spinning rods IMO.

i personally hate micro guides. Their ulgy to begin with and they dont improve on casting as advertise. but thats me....

I like very much the micro guides,the MATCH SIC guides and i have build many spinning long rods using these guides with long legs.
For one 10' rod i was using just 6 MATCH SIC guides,(not about 7-8 guides like for 7' rods find in the store)and the rod is very good and lite.

The long legs micro guides MATCH keep the line far from the blank ,so you can cast long distance easy.

Just about all my rods have micros they increase sensivity,cast farther,are lghter,and I use Power Pro Hollow Ace line when I want to use a leader.

Just a fad imo

Micros have been around longer than you think a friend brought a rod with mictos back from Japan 5 or 6 years ago. He said they were using them when he was sent over there 2 years previously he didn't know how much before that.

i love my micro eye rods, they cast much smoother and further for me.

Have 2 Falcon BooCoo's, 1 with micro's,, 1 without, both 6.10 MH
You can feel the diffidence in weight and The micro's are just more sensitive, "IMHO"
Their all I'll buy now
YMMV

I have using micro guides model "M"(match)for over 10 years for building my spinning rods.
30 years ago i was fishing in Europe with match rods with micro guide.