I remember reading this topic many years ago, and as i was on Cyrene a few months ago, i tried out harvesting and really liked the skill gains i got.
I do tracking almost everything ped gained and spent ingame, except 2 things, warps and harvesting, they are just so rare and so low i just ignored them and not tracked
But because of not tracked, i had no idea after 1-2 weeks of daily harvesting if its worth the time, or i just basically pay the chip-in cost in form of tt loss instead,
so this week i did a test, and as it may helps for others, i will write the numbers below:
Around 15 hours total, with Cyrene TT tool on small and large trees, and PH3 on the few huge trees,
using 10% skill pill whole time.
436.06 ped tt used and 407.96 ped tt returned, which results in 28.1 ped lost.
27.66 ped tt is the long moonleaf board which is have 198% yearly mu, rest went to the TT console.
also found 300 fruit and a few stones during the harvesting
That 3 basically would cover the TT loss.
Skills, i made notes on first day about all the skill points starting value, and now as finished, checking the PED value i got, by using this calculator
http://www.entropiawiki.com/SkillCalc.aspx as i find the PED value to share more usefull than the actual skill point gain, as that is depending on my actual skill points.
Analysis - Extracting, ESI needed: 4.56 PED, Final chip size: 4.10 PED
Zoology - Extracting, ESI needed: 1.48 PED, Final chip size: 1.33 PED
Biology - Extracting, ESI needed: 2.01 PED, Final chip size: 1.81 PED
Genetics - Extracting, ESI needed: 1.09 PED, Final chip size: 0.98 PED
Perception - Extracting, ESI needed: 3.17 PED, Final chip size: 2.85 PED
Alertness - Extracting, ESI needed: 1.18 PED, Final chip size: 1.06 PED
Dexterity - Extracting, ESI needed: 1.08 PED, Final chip size: 0.97 PED
Athletics - Extracting, ESI needed: 1.34 PED, Final chip size: 1.21 PED
Geology - Extracting, ESI needed: 1.73 PED, Final chip size: 1.56 PED
Resource gathering - Extracting, ESI needed: 10.74 PED, Final chip size: 9.67 PED
Botany - Extracting, ESI needed: 1.54 PED, Final chip size: 1.39 PED
+ intelligence attribute gains
Esi needed to extract all of these skills, except the useless resource gathering and botany skills:
17.64 ped, with 1k% mu 176.4 ped.
MU remaining after the 10% loss
in case those skills extracted and sold, total:
358.49 ped
So if i consider the TT loss compensated by long moonleaf boards + fruits + stones, ignore the useless skills (which some claims to be sellable at good price but i refuse to calculate with them) the difference on ESI purchased and skills sold at current lowest prices,
would be 182 ped profit, or cost to chip them in.
Divided it by the 15 hours i needed for them,
it is 12 ped gain a hour, probably not the best one could do, but sure beats sweating in case you are looking for a new way as F2P to make ped for your gameplay.
As a free to play player, just sweat as long as you can afford a small esi, start harvesting, sell the skills.
Dont forget the ESI cant go under 10 ped TT or you will get back ped instead of new ESI, so it is recommended to get a bit bigger one, like 20-30 ped TT and sell it when its close to 10 ped.
GL and have fun.
! 
Maybe when I repair skill.
