Would an SIS-style police unit be effective in other departments in the US?

The LAPD has an elite detective unit called the Special Investigation Section (SIS) which conducts surveillance on habitually violent criminals. One of their key methods is to wait until the actual commission of a crime, and then apprehend the suspect(s). The idea is that unless an actual crime is committed, the perpetrator is much less likely to be convicted. Sometimes, SIS officers are able to use deadly force should the situation call for it. Does anyone think such methods are effective in fighting crime? If so, would such a unit prove effective in other police departments around the country? What are your thoughts?