The short answer is yes, you can use
But since it looks like you are backing up a running system, which will include changed (log-)files, you are IMHO better of sticking with
rsync, which handles changed files by sending (compressed) deltas, not by uploading complete new files.
You can use a script that repeatedly runs rsync. The first
rsync will take long time (determined by the network speed and size of the source), the second and following runs much less time as only changed, added information is being sent.
lftp will unlikely be significantly faster on the first "transfer" and slower on the following ones.
You might also want to look at
rdiff-backup, which usses the rsync protocol underneath, but also can preserve deltas to roll-back to previous states (at the cost of extra disc space on the destination host).