To answer your question..the Indy4x lift is just as good, and IMHO better then the Calmini. The A-arms in the Calmini lift are designed to more easily get your vehicle aligned back to spec. They don't do much beyond correct the geometery to allow spec alignements. The balljoint flip accomplishes the same thing. It allows for spec alignement without the A-arm.

2 main reasons Indy4x's lift is better then Calmini's:
1) Customer Service....Calmini is terrible with their CS (I am a purchasing manager for a vendor of their product and they treat us wholesaler/retailers just as bad as their customers) I have yet to hear of anyone having a good experience with them. I can also attest to the poor Customer Service from a Resalers perspective. Not too mention that Calmini will probably leave you waiting for a good 6+ weeks for their product. Matt most likely has most if not all parts available quickly and will get you the kit within a very timely manner. Not to mention that Matt(owner of Indy4x) is great to talk to on the phone if you have questions, and proudly supports the Isuzu market and has for years.

2)Quality...while Calmini overall makes a quality product, it is more in lines with what their products lack. For example...the replacment crossmemeber. It is designed to be straight, and not have the curve design of stock. This is a PIA because it gets right in the way of the oil when you drain it. Also, their A-arms have a tendency to go through bushings regularly as well as squeak a lot. Then there is the issue, that quite a few people I know running the A-arms have issues with their alignment shims slipping out over time. I can't say it is directly related to the A-arms, but I only here of it with people who run them, and not those running stock arms with a balljoint flip.
Matt's kit will include all the parts you would NEED to do the lift. You can build your own in reality, but Matt has spent the time and put together a package the comes with all you would need for a complete kit. You can piece it together and only use parts you truely need to get the lift done, but a complete kit is a better way to go. It is like throwing a 4" kit on a JK...sure you can do it without long arms..but most people will tell you, if you can afford to get the long arms..do.

So, all in all, the kit Indy4x sells is just as good, and in most Isuzu enthusiasts eyes better. Mainly for what parts it doesn't have since in reality they aren't needed and seem to cause more problems down the road anyway.