I haven't seen Higgins much but what I have seen has been impressive.
As for Eaves:
Eaves' offensive potential outstrips his physical play, although he is definitely fearless when it comes to playing along the boards and in the crease.
He generally takes a beating in every game that he plays, which could put a damper on any future potential if he becomes injury prone.
However, his playmaking and offensive awareness, not to mention his shot, signal to me that he has top 6 forward with solid two-way potential written all over him.
He already complements other players like a veteran, finding a role with any linemates and excelling at it.
What's interesting is that Eaves had a poor training camp and was one of the first sent away from the team. Bochenski was considered the mega-prospect given his production in pre-season. Eaves earned a spot on the roster when injuries developed and by the New Year, could not be sent back down due to his value and ability to play in any role on any line. Bochenski was eventually deemed expendable due to his relatively one-dimensional play.
Ottawa has a number of these interchangeable players (Kelly, Vermette, Eaves, Smolinski) and it provides a lot of options and redundancy.
In terms of his offensive mental game, he is already showing a talent that outstrips players like Schaefer and Fisher, and a work ethic along the lines of Vermette or Alfredsson. To me, that suggests that he will eventually be a better fit on the top 2 lines than a 3rd line type role.
What will be interesting is seeing where players like Vermette and Eaves will be playing next season, given the preponderance of offensive talent already on the Sens roster. On other teams, they might be already playing in the top 6.