I would go with the woven one, which will give more flexibility to the pad, more absorbent ability, and be MUCH easier to clean.
Hard pressed felts are not as flexible, and need “hand, dry cleaning” to come even cleanish. They don’t do real well in washers, come apart in layers, the flat sweat and hair marks just stay on wool pads and even the white synthetics. To get those marks off, you have to dry the pad, then brush, curry, comb, to break up the dirt and sweat, then brush it off, vacuum the areas clean.
I have some experience from childhood days of cleaning the common hair and felt pads used both Western and English, all-wool felt, shaped saddle pads used for English riding so they were CLEAN and didn’t sore up the horse’s back for the next ride.
With the woven pad, removable insert, you should be able to wash it fairly easily because it is flexible in the water. Might still want to brush it hard to remove sweat and dirt before you get it wet. Use cold water to wash, and DO NOT do a lot of agitation to the wool, it will turn INTO felt as the fibers rub and stick harder to each other. I would rinse at least twice with plain water and hang to dry with good support under the pad to not stretch it out. Maybe lay it over a barrel side or a 5-gallon bucket while drying. Might take a couple days drying in the shade, away from moths who might lay eggs in the wool, and not overheating in the sunshine of a hot day.
The wool insert probably won’t need washing as often as the cover, just vacuum clean while waiting for the cover to dry, then put them back together.
Let the pad and cover dry totally between uses, they will last longer and be more of a good cushion to ride on.
Natural fibers are great things to use, just take more careful attention than synthetics will, to last well doing the job you bought it for. This is why folks LOVED when synthetic fabrics were invented, so much LESS work, no ironing! I have some 40yr old Navaho wool blankets with a lot of use, still thick, not felted, nice soft feel in your hands. But I never let them get crusty with use, did the careful washing to clean them. Never had a sore horse under them either, long or short rides.
