Interesting to read your comment regarding the lack of taste of Grapefruit-Seed-Extract in Nutribiotic tablets. I assume by 'taste' you mean bitterness. I know they used to make Grapefruit-Seed-Extract from grapefruit seeds alone, but now use pulp as well. I'm only guessing, but perhaps when they first released their Grapefruit-Seed-Extract product it was 100% seed extract and came in drops only. This may explain the bitterness of drops. Perhaps the tablets are made more from the pulp and this may explain why they are less bitter.
Since the effectiveness of GSE is most likely due to the added preservative and not the grapefruit seed (or pulp) extract itself, I wonder if it matters that the tablets are not bitter, assuming it is the grapefruit seeds causing the bitterness and not the preservative.
You may be right in saying the drops are better. Just not sure that taste alone is a good indicator of effectiveness.