Steve Jones has another thread on this. Research is clear on HIIT burning more fat over time, but there isn't much to go on in terms of muscle preservation. There is a study showing fat loss and muscle gain on HIIT protocol, but it was done on obese women so...
I still prefer high intensity/HIIT. Weight lifting is a high intensity interval protocol, really.
The synergystic effect (EPOC) of HIIT means you burn calories more throughout the day, so assuming you are relatively well fed throughout the day, I wouldn't understand how muscle catabolism would be an issue.
I like the idea of lifting, going to an immediate HIIT workout, then doing low intesity the next morning, rinse, repeat. Eat good pre and post workout nutrition, etc.
Who am I to suggest all this? A newbie schmuck who reads a lot, so certainly don't take my word for it!!!