Heya. I was tired of trying to dissect set strengths based on individual enhancers, so I added up the enhancement percentages for each set. There were some requests to see the chart, so here it is.
http://www.captainspud.com/coh/IO_Set_Enhance_Percents.xls
-Doesn't include set bonuses
-Only has sets available at 50
-Doesn't include travel sets
-There is no 4th caveat
I hope this helps your decision-making.
For those who really care about this sort of thing, I thought I'd add a link to the Paragon Wiki page that gives additional info on the Set Bonuses.
This is the starting page. (http://paragonwiki.com/index.php?title=Invention_Origin_Enhancement_Sets)
This page explains the color coding and gives hard numbers. (http://paragonwiki.com/Invention_Origin_Enhancement_Set_Bonuses)
Ultimately, a set that has lower individual enhancement percentages tends to make up for this by giving more substantial Set Bonuses.
It's an interesting additional layer of number-crunching for those that like the exercise.
As an example, a full set of Scirocco's Dervish should provide set bonuses of:
+10% Regeneration (passive bonus)
+3.125% Negative Energy Resistance (passive bonus)
+3.125% Global Accuracy Boost (to all powers)
+3.125% Defense to AoE Attacks (passive bonus)
+3.125% Defense to Psionic Attacks (passive bonus)
In comparison, a full set of Multi-Strike should provide set bonuses of:
1.65% Sleep Resistance (passive bonus)
+.945% Fire/Cold Resistance (passive bonus)
1.65% Stun Resistance (passive bonus)
+1.875% Defense to AoE Attacks (passive bonus)
+1.875% Defense to Melee Attacks (passive bonus)
And a full set of Cleaving Blow should provide set bonuses of:
+1% Endurance Recovery (passive bonus)
+1.25% Defense to Energy Attacks (passive bonus)
+1% to all Damage dealt (to all powers)