It is counter-intuitive perhaps, but the bonus starting techs actually speed up all other (human) research in the game. First, the starting techs do not count "against" you for the cost of future research. Even if you get 7 starting techs, the first new tech you research costs the same.
It is much more subtle, but the starting techs also help out greatly because if you and the reference civilization are on the same exact researched/obtained tech, you still lead by 7. Assuming you *give* say, three tech to the opponent, you still lead by four... BUT... now the COST of your research is MINIMIZED (a civ 2 algorithm) because the game only tracks the techs you have obtained from the start, compared to the reference AI civ's progress since the start.
You can therefore be AHEAD in research, but actually get the built-in "bonus" (actually, just the cheapest cost) for being "BEHIND" in the tech race. This can make a huge difference is research costs throughout the game. Even if you are ahead in researched/obtained tech, the penalty for being ahead is reduced, so once again, research is cheaper thoughout the game if you have those extra starting techs.
Conversely, if your opponents all get free starting techs and you do not, you will have a continual, long-term penalty in research cost for the same advance...
Also, pollution is a function of starting techs. Any techs you begin with do NOT count into the complex pollution calculation... every advance you discover/obtain yields an incrementally higher chance of pollution, but I won't go into the details here.
In summary, starting techs are:
1. free tech
2. cheaper tech in future research
3. less pollution probability
So my preference is generally for the extra starting techs.
