@Riastrahd foremost, thank you for your service. Also, I wanted to share this link with you because I asked a similar question last year and there are some real gems in that thread (for example
@WhatWouldHulkDo in post #9 with his "jar of rocks" analogy, which I still refer to often). I thought some of the input might be pertinent to your question. Note in my opening post that I said exactly the same thing that you did regarding how kettlebells make me feel:
Kettlebell - Another Crossroads (Barbell or Kettlebell!)
My own thoughts: you were doing strictly barbell work for a decade, and now doing kettlebells for 8 weeks, it's not surprising that your body is getting a different type of adaptive response that feels almost 'nourishing'.
My $0.02 about kettlebell and barbell work: barbells give you the overall strength that comes from heavy, bilateral multi-joint movements, but can also introduce imbalances through not differentially strengthening the dominant and non-dominant side. Going back to the jar of rocks analogy, the barbells are the big rocks, they will give you tremendous benefits in the areas of strength (or power, if doing o-lifts), but kettlebells are great for nailing down solid movement patterning, and also for practicing unilateral work, which barbells don't offer the same opportunity for. Even if only doing bilateral work, kettlebells often do "fit the contours" of your movement more closely than barbells, because of the position of the CG in reference to yours.
A poster above mentioned the CG of the kettlebell vs. the dumbbell. When gripping a dumbbell the CG is right in the middle of your hand, so when doing an overhead press (for example), you are pushing directly against the CG of the dumbbell. When doing an overhead press with the kettlebell, the CG is offset, so you are not only fighting against gravity, but also fighting against the tendency of the kettlebell to want to pull away from your body, which activates shoulder stabilizers more than a dumbbell would. I think this is great for shoulder health. I also personally prefer to use a KB vs. dumbbell for overhead movements because you are less likely to drop the KB vs. the DB. I always hold my breath and hope for the best when I see someone do a TGU with a dumbbell. It doesn't happen often, but it's memorable when it does.
I think the best approach is to consider the combination of strength and longevity. I do believe that if only chasing raw strength, barbells are more
efficient than kettlebells, however if a combination of strength, mobility, stability and longevity is your pursuit, then a blend of multiple training modalities is best. Which rocks you decide to put in your jar and when is probably best decided based on the feedback that your body and your strength training journal is giving you. Good luck!