For what it is worth, I have replaced the original brass footers that came with my HT3s with six Mapleshade threaded thick carpet-piercing heavyfoot footers because I have (wait for it) thick carpet that needed piercing.
The original footers are not slouches (nothing on an HT3 is) -- big heavy brass monsters. And I would guess the aluminum ones are similar. These probably are the best footers for most applications. But by design they have a rounded bottom and do not dig into the floor under the carpet and pad. Since I do not have finished floors under my carpet, I could use a pointed footer and not worry about floor damage.
So enter the Mapleshade footers -- big heavy brass monsters with nasty sharp points
http://www.mapleshaderecords.com/audioproducts/heavyfoot_threaded.php. The version I ordered are tapped for 3/8" by 16 and come with brass studs (don't order hanger bolts). They are a direct swap for the original footers.
Result: The HT3s are now more stable and seem to be literally "stuck" to the floor. The Mapleshade footers are a little larger in diameter than the original footers but still fit under the edges of the plinth and do not contact the heads of the carriage bolts used to affix the plinth to the speaker bottom. The new footers are the same height as the originals (2-1/4") but caused my speakers to sit a
little lower since the footer is not sitting on top of the compressed carpet and pad.
Are they worth $47 a piece? Well, that is expensive for a hunk of brass (especially when I found Harbor Freight close-out brass plumb bobs make good footers for $1.50 a piece). But they are the right size, nicely machined, and come in the thread size to match the HT3 plinth -- so there is something to be said for appearance and plug & play. Plus I love my HT3s and prefer the more direct connection with the floor. Your mileage may vary.
And if someone finds another footer that looks good and is as easy to swap as these (subjective measures I admit) for less -- please post your findings -- I'm sure I'm not the only one out here that likes pointy feet -- more options for the next guy.
David