I don't think 4 ts is enough to make a substantial difference. Things might start happening if you guys increase to 2 tbs.
Agreed. I think it's a very good sign if you don't get any flatulence from 4 teaspoons of RS (4 teaspoons = 1.3 Tablespoons). That's a pretty good sign that you can ramp up quickly to 2-4 Tablespoons/day and get the fermentation to move towards the distal end of the large intestine. I didn't get any flatulence from 2-3 Tablespoons/day and only got a little flatulence from 4 Tablespoons.
The idea is to eventually get to a point where you have a little non-smelly flatulence throughout the day — which is an indicator of butyrate production. I believe the output should be mostly hydrogen, if I'm not mistaken, which shouldn't really smell.
If you never get flatulence — even at 4 Tbsp/day, you may need to introduce a few SBO probiotics or fermented foods to get the seeds in place. But, even if you don't have flatulence, you can still get some benefits. You just get more benefits when there's a little bit of flatulence.
In general, the off-gas from fermentation is eaten up by cross-feeder bacteria (it's believed they swallow the gas as fuel and do other good things of you). So, over time, the cross-feeders will get in place, and bloom, to calm the flatulence down to something that you barely notice. In other words, it becomes a balanced eco-system over time.