I'd like to compare swype versions between 2.3.15 and 2.4.0.
If you have 2.4.0 installed what version do you see in Applications>Manage>All Apps for Swype?
in the 2.3.15 leak the version number is: 1.64.40.9380
1.64.40.9380 is the version that came with R2D2. Just checked in the APK and that's what it states.
Strange you are having problems with it...
Did you try
adb shell
su
mount -o rw,remount -t ext3 /dev/block/mmcblk1p21 /system
rm /system/app/Swype.apk
pm uninstall com.swype.android.inputmethod
and then reinstall it?