2 hours ago, Team9nine said:

Neither - I’d typically run 6-10 lb. leader in your example.

Not sure exactly why that’s “neither”. If I’m reading charts correctly, 20# braid is equal to 6# mono as relates to diameter. 10# braid is equivalent to 2# mono. I’m not sure if a 6# leader is appropriate for 20# braid, but I’m pretty confident that a 2# leader is not. So what’s really the rule of thumb? Or is there none?

You basically asked if you should use 2-6# or 10-20# leader.  Neither.  I'd say right in the middle, too: 6-10# for just about any spinning application.  I usually roll with a spool of 8# Blue Label leader material.

Good enough! Went with Sufix 832 20# and 8# FC leader. Reel is due tomorrow. No shipping date on the rod yet. 
 

This will be my first use of braid. It sure feels different. I’ll use some 8# hybrid as backing on the spool. 

Well I'm running Sunline SX-1 12lb braid as my mainline on my finesse spinning setup which is fairly abrasion resistant for a thinner braid and I usually use a 6lb leader. I prefer braid on spinning reels -- typically less line twist issues and I rarely get wind knots, but straight fluorocarbon/mono is also a possibility. Seaguar Blue Label is a great leader line, but to be honest most of the time I cut off some 6lb line from a Berkley Trilene Fluorocarbon spool that I buy every spring, buy one get one free.

 

Now if you are fishing weightless larger worms, you may want to step up to 20lb braid with a 8lb or even 10lb leader. 15lb braid and 8lb would be the happy medium between weightless slightly larger worms and finesse.

59 minutes ago, Boomstick said:

Well I'm running Sunline SX-1 12lb braid as my mainline on my finesse spinning setup which is fairly abrasion resistant for a thinner braid and I usually use a 6lb leader. I prefer braid on spinning reels -- typically less line twist issues and I rarely get wind knots, but straight fluorocarbon/mono is also a possibility. Seaguar Blue Label is a great leader line, but to be honest most of the time I cut off some 6lb line from a Berkley Trilene Fluorocarbon spool that I buy every spring, buy one get one free.

 

Now if you are fishing weightless larger worms, you may want to step up to 20lb braid with a 8lb or even 10lb leader. 15lb braid and 8lb would be the happy medium between weightless slightly larger worms and finesse.

I'm putting together a finesse rig. A Dobyn's Sierra 692 with either a Sahara 2500, 1500 or Excelor 1500 (I have all 3). I was thinking your last suggestion with 15lb braid & 8lb FC leader would be just about right. 

6 hours ago, BrianMDTX said:

Good enough! Went with Sufix 832 20# and 8# FC leader. Reel is due tomorrow. No shipping date on the rod yet. 
 

This will be my first use of braid. It sure feels different. I’ll use some 8# hybrid as backing on the spool. 

No need to use the good stuff as backing.. If you have some decent mono, use it.   I use old spools of big game.  

16 hours ago, BrianMDTX said:

Good enough! Went with Sufix 832 20# and 8# FC leader. Reel is due tomorrow. No shipping date on the rod yet. 
 

This will be my first use of braid. It sure feels different. I’ll use some 8# hybrid as backing on the spool. 

That'll work well.  Braid is different for sure, but it seems easier to get along with on spinning gear.  even the slightest wrist flick will set the hook.  Good luck, and enjoy!

10 hours ago, Teal said:

No need to use the good stuff as backing.. If you have some decent mono, use it.   I use old spools of big game.  

This is good advice.  I put backing on most reels.  When you are using 10 lb braid (2 lb diameter), I have 80 yards of 8 lb mono as backing and then about 75 yards of braid.