Calmini's good points are that it's a specially engineered package for Isuzu, everything is supposed to work perfectly together, and it's really a great value (bent left upper rear link, trac bar, new crossmember, front upper arms, steel brake lines, ammos&shocks, lots of smaller goodies - all under $800). But Indy4x and Darlington offer much more flexibility in their offerings. You can choose exactly what you want for exact price you can afford. And you actually can find much better details than what Calmini suggests:
- Rear links from Stinkyfab are better than Calmini's ones
- OME coils are better than Calmini's ones
- Rancho or OME shocks are better than Calmini's
- etc

The only exception is the Calmini's front control arms, nobody else does them.

So, the Calmini's advantage is that it's a complete package of good engineering for a relatively modest price.

I do not believe that you need Calmini's "completeness" if you do not 4-wheel much. Many their core details address the truck's behavior off-road, which is not what you need.

The only thing I ordered from Calmini is their front control arms, almost everything else I ordered from Indy4x (not as a package, but as separate details what I needed).

One detail: after any lift, do not forget to install a new longer HD trac bar, it will improve the handling.