Gold or silver? With silver your time is worth more than metal recovery. With gold for me it is the other way around.
If I tree up with plenty of space I can cut the sprue from the tree then cut the feed sprue from the piece. End cutters I have found I can get the closest without harming the piece. The best I have found is the Bergeron compound end cutter. Goes through fresh cast silver and 14kt like butter. White gold it can chip the blades.
With gold I am trying to save all the metal I can and find a file and country music work best. With silver I use a white silicone wheel on the flexshaft, breathing filter is a must, and Lynard Skynard music. Time is money and I don’t care about the silver recover plus the silicone makes a mess but no heat.
I’ve experimented with all kinds of cutters. Bold cutters meant for steel cut through 12-15mm sprues for recasting with ease. I’ve got doctor pin cutters for stainless and titanium that cut through feed sprues. Metal wire cutters, nail cutters, The Bergeron work best for me with older arthritic hands.
When I’ve bought clip and ship castings from a professional casting house I am amazed at how close they cut the sprue. It only takes a couple of swipes with a file. I’m sure those are hydraulic cutters with special tips that are sharpened on a regular basis. If you are on the mid-Atlantic area and want to try a few different cutters, give me a private message.