you're actually free to use the latest version if you want, just download the latest LAME 3.9x exe file, and replace it with the file in Program Files\NCH Swift Sound\Components (mp3el.exe - rename the lame exe to match this name).
thats it, switch will now use the new lame !
we're currently deciding whether to "ship" the latest LAME with switch, we usually won't do it unless it does something that the older version can't do (or doesn't do as well). the latest LAME looks quite good so theres a chance we'll do it.