Out of the Boa Constrictor Imperator sub-species, the Nicaragua locality are considered true dwarfs. In adulthood they can reach up to 5-5.5 feet and -very- slender.
They present a -deal- less danger than Colombian locality boas because they are way thinner and with much less mass. Heck, I have a couple of 2-2.5 year olds that are at the size of an adult Cornsnake.
There has been no report of a death or severe injury caused by a Boa Constrictor Imperator though... so I wouldn't worry that much even about Colombian Boas, let alone Nicaraguan.
A few things to note- they get way smaller, they can be nippy(they are actually a bit more prone to that as babies than Colombian Boas because they are less removed from the original wild population- less generations passed), they can be picky eaters and need an understanding keeper- they are a -bit- like Ball pythons, just a bit less so... You need to know not to get worked up about them skipping a meal or two without trying to force-feed them.
Read up about them, they are awesome.