I originally bought a bmg, small bucket, and stump grinder for my sk650. Since then, I added forks to shuffle slabs, and I occassionally use them to shuffle equipment on pallets, carry a 50-gallon spray rig, offload shipments from semi trucks, carry alturna mats, etc.
The bmg is the money maker.
The others are more about money loss prevention and logistics. I've probably broken even on stumps by now, but I have secured several contracts by being a "complete-job" company. I also get paid quicker by grinding my own stumps vs. subbing. The bucket is a useful implement for planting 4" b&b (my max tip weight b&b), infrequently used. The stump grinder + shovel can accomplish the same task a little slower. I imagine that the grapple or a garden hose could as well. The main point is that - after getting a bmg - you just need to evaluate your operation, decide which attachments you need, and be aware of whether they make money, reduce the loss of money, or are a shiny that loses money. It's hard to sell them once you have them since mini plates are still a bit uncommon. Hth.