I spent the last weekend using the Anvil 30 ballhead on an RRS Series 1 tripod to glass for elk in the backcountry. This combination is possibly the best balance of weight and stability. By opening the tension clamp most of the way you can smoothly glass with a spotting scope. The clamp also locks down solidly and holds my 14 lbs precision rifle without issue. I love the fact that the Anvil 30 works seamlessly on both ARCA/ SWISS and Picatinny style rails.
My only critique is that I wish the ballhead was lighter. There is plenty of material that could be removed without affecting the functionality of the unit. Granted, this would add machining cost for a very niche user group (backcountry hunter). Then again, if you’re buying RRS products you’re probably more concerned with quality than cost.