I mixed up a 16.5:1 (water:concentrate) eGoo mix with some added baking soda and citric acid, and a guar quick mix with 1/4 heaping teaspoon Bob's Red Mill Guar Gum per liter water, 1/2 heaping teaspoon baking powder, and 40 grams Dawn Pro per liter.
The loops were 100" top-strings. One was webfoot microfiber top with 2-strand rayon bottom. The other was a full-ply rayon mop yarn top and t-shirt yarn bottom. Both have done great with the HEC juice lately.
Temperature was 55F and humidity about 90% according to the nearest Weather Underground station. My humidity meter read just over 80%.
After 6 dips, I gave up on the eGoo. I couldn't close a bubble. With the guar, I created a few giants but they didn't last long -- surprising given the conditions. But sometimes, what seem like great conditions don't create great bubbles (due to some unknown environmental factor).
I added some of my standard HEC mix (see the Recipes page) and both mixes started creating nice giants and super giants. I didn't have much time. So, I didn't get a chance to try the HEC mix on its own. (The HEC this time was Natrosol 250HHR). I don't know how the mixes would have compared to HEC on its own.
My gut tells me that the HEC/guar combination might have been a real winner, but the only way to tell will be with some actual head-to-head competition,