Well after burning a few spined kits to get the feel for things I'm starting to understand how this plays with Imbuing and how Enhancing still plays a roll and why I might want to sparingly use a Forged Metal too, etc.
Using just the Spined kits I was able to make some pretty nice pieces and avoid using any high-end imbuing ingredients at all (not counting the 4 relic frags per piece for 7 LMC but I don't consider this high-end since I easily farm that many in Shame or Wrong in about ten minutes or less). I didn't have a Forged Metal tool so I destroyed tons of stuff with my enhancement attempts but overall my luck wasn't too bad. I also didn't PoF anything up first since I was just playing around and didn't want to destroy PoF'd armor on enhancement. I was also pretty conservative with the low-end ingredients.
My goal was to build a basic, leather armor, "throw-away" suit for my still training Sampire. Throw-away because I wasn't PoF'ng or using high-level ingredients until I figured out the most efficient ways to use them with reforging. My process was basically something along the lines of:
1) First I created a spreadsheet to work on the suit build. I know, may seem obsessive but it helped immensely!
2) Figured out what non-crafted items I would be using and added all properties to the spreadsheet. This gave me the remaining resists, etc required so I could best figure out how to map out the pieces.
3) I created some exceptional leather armor pieces and started putting together items that fit the resist requirements while attempting to minimize my resist imbue requirements
4) Because I was building a suit to be in Vamp form my Fire was roughly -6 without the use of 4 armor pieces so I knew that Fire was going to be a resist Imbue on most of the pieces (this was before I played with reforging since I had no runic tailor kits). Poison was my next lowest but I knew I wouldn't need to Imbue poison on all the pieces.
5) Imbued Fire on a piece, then enhanced with Barbed to get the most resists that I could. I learned that with this method you don't need to max out the Imbue and use Boura pelts (or whatever) but the enhance would still max out the resist, e.g. imbued 17 Fire then the Enhance brought it up to the Cap of 19.
6) After all this I ended up at a place where I needed just sleeves but the resists needed to be something like 6/19/8/19/5. I didn't want to burn 2 imbues on resists so I broke down and bought a 10-pack of Spined Kits.
At this point I was focused 100% on making sleeves via the reforging process that would finish off my suit, learning more about armor reforging in the process.
I figured out a couple things, maybe not all true

1) There doesn't seem to be a reason to use Structural or Fundamental. I suppose if I were making training suits or something where the Brittle and no repair didn't matter I would explore these but I figured Shame loot has this stuff covered already.
2) If you want to overcap a resist, don't choose 2 names - only choose 1. This seemed to bring up the intensity of the resist dramatically and there were no other crap mod's wasting Imbuing slots. With this in mind it becomes nothing more than making exc leather sleeves and reforging until I got the high Fire I was looking for. I was getting mostly 20+ in either Cold or Energy for whatever reason, I even got one piece with 19 Energy and 23 Cold. Finally I hit 24 Fire on a piece and decided this was the one.
3) It may be possible to craft a piece with Spined that hits a high-end cap - for example, 150 luck instead of 100, but apparently don't count on it.
4) Unlike Imbuing, it seems that the reforge-generated resist DOES NOT work against the enhancing cap! I ended up enhancing this piece with Barbed (and with my eyes closed I might add since I must have lost 20+ sleeves through this whole process (I know not that many really but I'm still playing low-end here so it was frustrating)) and wound up with 27 Fire! I don't recall which now but I also ended up with another resist at 19 so at Imbue time I ended up with two Imbue slots burned. However, I had unimbued sleeves with the neighborhood of 75 total resists! Not too shabby with a Spined kit.
At this point I Imbued LMC/Mana/Regen on all the pieces and newly armed with my test suit that cost me nothing that I didn't already have from training Imbuing and unwravelling Shame loot (and the $1 worth of IRL cash for the Spined Kits I burned).
The next suit will start with Reforging the leather pieces instead to get the resist caps that I want. I think I'm getting it now...
X