Probably a stupid question, but is the soundtrack to Tenchu Senran less 'atmospheric' than the last two (And probably the original)?

It's still mainly atmospheric overall, sticking with the basic Tenchu formula...

N.Asakura isn't present this time around though, instead we get a hodgepodge of 4~5 people.

The more cinematic~atmospheric tracks are by Koichi Suenaga,
The more memorable~medolic tracks are by Yoshikazu Takayama,
just a few are by Hideyuki Eto and Sayako Nanya

My fav track after once-through is 11. Clan Watchtower