First off I'm not a SWAT team member. The trainers at the last "how to clear a building safely" course I attended were. They showed a variety a techniques, presenting the pros and cons of each. To paraphrase them:
The entry is dynamic and fast.
The first guy through the door enters this way. He is to transition to a conventional hold if no threat is in the immediate vacinity. If an immediate threat presents itself past three feet, yes, take the shot as available, but suprise should be on his side, so he should be able to transition to a weaver hold quickly and put aimed shots on target. If a BG is within arms reach you are to react as necessary, placing an emphasis on weapon retention. So block, grab, shove, strike as you need to.
It is important to remember that there is a difference between patrol officers, joe citizen, and special tactics/SWAT team members. The entry team is well trained, well armed, and extremely comfortable working together as a cohesive unit. As such, the first guy in relies on those behind him.
An important note, the SECOND guy in usually gets shot. This has to due with the BG's reaction time.
Frontsight - sort of. The guys I know who do it all hold their arms so that their hand is somewhere between the vacinity of their shoulder to their ear.