It's in fact very, very hard to accurately measure "range" with these quads. Even if you fly in the same spot, conditions may vary quite a bit. Even if the spot is a remote, flat inland area without other MW interferences or buildings or trees, other things affect range. These differences are also rather small to be accurately measured considering the variation in conditions.
Windsurfers and panels do help a bit. Many times we get the placebo effect, because of the difficulty in measuring range in any scientific, reliable way. SO a good flight may lead to think "wow I've doubled distanced here compared to X and Y" when in fact it had little relation.
Light bridge is pretty well engineered as it is. FWs and RC versions do have small differences indeed. I've tried most boost options currently available, and in my experience the only thing that makes a real, significant and measurable impact in signal strength - thus affecting range, penetration or whatever one may need - is a powered booster.
If penetration and signal stability is important, that's fine. If distance is the goal, a battery mod is definitely needed because in original form autonomy, and not signal interruption, has been the limiting factor every time.
All that is to say you mayor may not feel a difference (I had the same issue and didn't...), but you should be fine with your C Tx either way if your needs are nothing in the exceptional range.
