As far as I can tell there are no known collisions for the full hash.
Lessfs uses the full hash so there seems to be no reason to switch to a
slower sha2 algorithm.
Tiger is a cryptographic hash function with a 192-bit hash value. It was
proposed by Anderson and Biham in 1996. Recently, weaknesses have been
shown in round-reduced variants of the Tiger hash function. First, at
FSE 2006, Kelsey and Lucks presented a collision attack on Tiger reduced
to 16 and 17 (out of 24) rounds with a complexity of about 2^44 and a
pseudo-near-collision for Tiger reduced to 20 rounds. Later, Mendel /et
al./ extended this attack to a collision attack on Tiger reduced to 19
rounds with a complexity of about 2^62 . Furthermore, they show a
pseudo-near-collision for Tiger reduced to 22 rounds with a complexity
of about 2^44 . No attack is known for the full Tiger hash function.
In this article, we show a pseudo-near-collision for the full Tiger hash
function with a complexity of about 2^47 hash computations and a
pseudo-collision (free-start-collision) for Tiger reduced to 23 rounds
with the same complexity.