Current devices have four times the available RAM of the Streak, thus the RAM consumption is a non-issue. Honestly, I never used the Swype keyboard for its Swype features, but for its key size, as the stock keyboard sucked wind in that regard. As a consequence, I didn't try other keyboards on the Streak as there was no need for me to do so. The included Swype did everything I wanted it to do.
My third-tier Chinese-manufactured tablet doesn't use Swype, but Thumb Keyboard. It works fine and can be skinned, but that tablet's Allwinner A10 processor seriously lags compared to the Streak's Snapdragon, which is why the tablet doesn't get used too much even though it has a 9.7" screen and runs Ice Cream Sandwich. If memory is a concern and you don't need or use the Swype feature, Hacker's Keyboard likely will work just as well.