I have used the heavy Fuji fluoro tapered lines on the Daiwa Expert LT and Nissin Seikon Becchou 7:3 rods for windy conditions, but mostly use fluoro or nylon level lines. Just about any decent 6:4 or 7:3 tenkara rod will cast and fish even #2 fluoro or #3 nylon just fine, just takes a little (okay lots) of practice, but firmer 6:4 and 7:3 rods handle heavy tapered lines better.
One of my small stream rods the Tenkara USA 6:4 Iwana cast the #3 nylon just fine but is not over lined with the heavy Fuji tapered lines which can be explained by T-Bums penny rating of 23 for the Iwana as apposed to the Oni Type I which is still a 6:4 rod in action but only has a penny rating of 13 making it more of a level line rod, one is a firm 6:4 and the other a soft 6:4 tenkara rod.
What it boils down to, if you would like to fish with light level lines you will not be handicapped with any good 7:3 rod and will have an easier time casting in the wind with both level and tapered lines. Even if wind isn’t a consideration firmer 6:4 or 7:3 rods make it easier to cast accurate tight loop cast in tight spaces if need be. For me personally the Nissin 7:3 rods are a better match, in the Oni lineup the Type I, 395 and new Itoshro work better than the Type II and III 5:5 rods.
The Daiwa level line rods are softer more mid flex rods like the Nissin Airstage/Royal Stage honryu rods but have stiffer hollow tip sections. The Nissin 380/390 honryu are very smooth casting rods but the wind pushes them around from the soft mid section, I sold mine for this reason. The new Daiwa Master L LL series sounds really nice, I will likely get one by next season, with the stiffer hollow tip section it may handle a breeze on my smaller streams just fine, if its really blowing something firmer like the Daiwa LT 7:3 would most likely work better.
So many rods so little time and money to try them all but I will keep powering through until perfection is achieved.