I had little free time and I compared few designs. So a bit of graph theory, which seems to be very useful if comparing to my tests thru years and the first reviews of commercial strutless kites.
2 tests, once on the same kite type (in my case lower AR open-C), with struts and w/o struts, once both vs. modern delta.
Stuts Vs. Strutless
Same size, same arc, virtually the same AR, but with different profiles and TE as you have to do it on strutless due to the fact of no structural support. Basically this graf represents the differences of the profiles used.
Strut kites can have deeper profiles (within the kite type...), moved more to the back and by that it can generate more lift, more moment. On the end differences are not so big. The most differences are on moments where the one with struts have more forward moment and therefore may sit more forward in the wind window, have beter depower and better upwind. This may also explain the windrange differences. On the other hand strutless is more (pitch) stable and vice-versa the rest. Struts will limit stress on canopy and by those kite will be more controllable at the small AoAs, with less problems "on the bar". C/D graph does not show much differences, only at small AoAs, with some drawback of strutless at very depowered kite. Don't know exactly if the difference comes because profile or TE shape (I believe both).
Compared to modern Delta...
Now, here things gets a bit more interesting. Basically this graph shows you the vs. between Delta and Open-C kites. More swept back wings allows the usage of different profiles so the power per m2 may be greater plus also other factors may be better.
Please note that these tests are only theoretical, approximation of XFLR5 software and its candies... Explanation is completely M2C, you should figure out yours on your own way.
This post will not tell you which kite is better to buy!