The following are the results of my tests. Like AJ, I used a stopwatch to test how long it took Culture to reach various points, with or without the research techs, as well as with a second culture tower alone (no add'l culture research). [BTW, these were at 2X times speed, and all faster settings, so double the times for actual time to reach the planets?]
Planet 1 took 59.44 with no research.....and 52.87 with confluence, 44.69 with second tower
Planet 2 took ~195 with no research......and ~168 with confluence, ~111 with second tower
Further, I examined the end game stats after 20 minutes of culture. The following summarizes the:
'Galaxy Culture Percentage' statistic by minute, for 1 Tower with no research (0%), 1 Tower with Confluence research (30%), and finally 2 Towers with no research again.
Galaxy Culture Percentage:
Time..1Towr..Confl...2Towers
Mins....0%....30%....0%
....1......5......5........5
....2.....12.....13.....15
....3.....16.....18.....23
....4.....20.....23.....30
....5.....25.....27.....32
....6.....28.....31.....34
....7.....31.....32.....36
....8.....32.....33.....38
....9.....33.....34.....40
...10....34.....35.....41
...15.....38....39.....48
...20.....41....42.....54
After some more thought, and the above testing, I've concluded its not worth investing in Confluence. Why? Because adding one more Culture tower cost much less, and gives much better culture spread. Confluence costs about 2.5X (times) of what adding another tower costs (ie: $900 100M 150C vs $2600 250M 350C). You can easily afford to even pay for more logistic slots.
