BAF LOC 23

I'm trying to figure out the BAF ILS 23 localizer approach. The normal
LOC 23 approach has a MDA of 900, and the LOC 23/DME approach has a MDA of
700 feet. After the FAF, there is a step down fix at 2.7 DME with a
_1160_ before it. So does this mean that if you don't have DME, you can
descend to 900 immediately after the FAF, but if you do have DME you can
only descend to 1160 until 2.7 DME? Why is it safe to descend to 900 in
one case, but only 1160 in the other?

--
Paul Tomblin http://xcski.com/blogs/pt/
My family's values included "Always state your assumptions and your evidence",
"first find out what the problem is, then fix it", and "feed your horse before
yourself". But you don't see people legislating those... -- Zeebee