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I've used both of these as well as the Simms.
Orvis supposedly has good ones too.
I've not tried them in felt.
The wearbars are the best for bubbleweed, the gripstuds go well in soft soled rubber boots and shoes (like boot foot waders), the simms are nice on slippery rock without much weed. If your felt has worn down the Simms might be too long. They come in a long version for felt and a shorter version for vibram.