I have experience with a few bullet drop compensated (BDC) reticles (Horus, Burris E1, etc.), but not the Holland ART. Holland offers several different reticle designs and sizes. I prefer a smaller reticle pattern so that the reticle is less likely to obscure bullet impacts. Other people like the larger patterns - it's a personal preference.
Even for the largest ART reticle design, the elevation holdoff is good for about 800 yds for 308 Win, and windage holdoff is good for about 600 yds (10 mph). Beyond that, you may need to dial additional elevation or windage. The smaller ones are limited to even shorter ranges. In my opinion, the limited windage holdoff is the only potential shortcoming of the ART designs.
You seem to be referring to the drop cards that Holland's software can produce. Most ballistic software can produce those drop cards for any caliber. Likewise, the Holland software can produce drop cards that work with other BDC reticle designs. Holland ART reticles are subtended in either 1.5 MOA or 0.5 mrad increments. That is similar to other reticles. With any BDC reticle, you can only aim using individual reticle marks at short range (<300 yds). You have to interpolate between marks to be accurate at long range (>300 yds). To reliably use any BDC reticle, you will need to practice with it.
Regarding accuracy, Holland' products are well engineered. I would expect ART reticles to be accurate.
Bottom line, if you upgrade your existing scope with an ART reticle, you've simply invested more $ in the same optics. If that's OK with you, then go for it.
