I routinely use sedline for TIVA cases. Definitely helpful for monitoring depth of anesthesia, both in terms of preventing awareness but also for timing wake up (oftentimes I've been able to cut my propofol dose lower than I otherwise would have guessed, leading to faster emergence at the end). I would caution you though, that it is definitely not a perfect monitor. The Sedline does NOT give you "raw" EEG"- it gives you a processed, compressed modified frontal EEG. Still useful, but the processing software is a bit of a black box.
We had a case of awareness recently (the bad kind- aware, in pain, afraid, with explicit recall) where the spectral array on the sedline looked for all the world like a patient under general anesthesia. A member of our department who does his research on EEG later took the data from that case back to his lab and got rid of the post-processing that the Sedline does (converting it back to a true raw EEG), at which point it became pretty clear that there was higher frequency low amplitude activity. This obviously would have been concerning had it been seen at the time. In this particular case, the pitfall was that the patient was elderly and had mild hepatic encephalopathy, both of which can decrease the amplitude of the higher frequency signals; the sedline presumably has a high-pass filter, among other things, because those ultra-low amplitude wavelengths were filtered out of the spectral array.
If you're using a Sedline and you're really worried about awareness for whatever reason, I suggest putting the Sedline on pre-induction and make it a point to get a good baseline reading. This involves taking an extra 30 seconds where no one is touching the patient, and you instruct them to lay still as possible with their eyes closed. Not something you necessarily wanna do for every case given it's a minor PITA, but on more than one occasion I've been surprised by how "anesthetized" a patient's awake EEG looks, and this has stopped me from using the EEG to be falsely reassured during the case.
