To me it’s not only a problem of expertise (that can be gained quickly by reading one of the many tutorials found online, it’s not strictly RT-specific). It’s mostly a problem of the amount of tweaking needed to process a single negative, let alone an entire roll. Specifically, having to tweak RGB curves was the most frustrating thing to me. After you’ve carefully set them up, if you touch anything that happens before in the chain (like exposure or WB), you end up messing up everything, so you’re limited to use Lab controls.
I guess some people have good “eye”, and can quickly get the settings right, and never touch them again. Personally, i’m terrible at that, i’m always uncertain or unsatisfied with my result, and get into an endless loop of tweaking 
Moreover, when i found the Wikipedia article i’ve referenced in the other post, i discovered that inverting the tone curve (or using the invert tool in Gimp) is just not the right math to represent how film works (hence the need for manual tweaking). So i thought: why not start with the right math, and then apply some manual tweaking? 
Please, can you share the make/model of the panel? I’m alway curious to try different backlights
This is exaclty what i do as well. My wheapon of choice is a cheap speedlight reflecting on a piece of paper. I had ordered a Kaiser Slimlight Plano, but i returned it because it wasn’t bright enough to shoot at f8, and didn’t beat my speedlight+paper setup in terms of “flatness”.
Please, can you post (or PM) one or more samples that are giving bad results? I’d like to investigate the problem