The trade matcher is great when there's up to a page or two of cards. It gets increasingly unmanageable as that list grows. I've looked at profiles where the trade matcher has literally dozens of pages of cards, and it simply takes too much time to wade through that.

Some suggestions for features:
-- a way to look at all matching cards at once
-- a way to set the number of cards shown on one page of the trade matcher -- currently this is capped at 25 per page. I'd like to see 100 or 200 or 500 cards at once.
-- a way to sort the trade matcher by set instead of by name
-- (a way to sort an agreed trade by set would also facilitate pulling cards more quickly)
-- a filter when looking at someone's want list: show only cards that are on my trade list (this could then be combined with other filters like edition, rarity, etc)

I second this. There are a few times even with 2 pages of cards I am wishing I can sort by value of cards as well.

The most impactful thing you mentioned for sure was adding a filter to their trade list for "Is on my Want List"

In that vein, should be able to sort their want list by "Is on my Trade List"