Yeah, I can totally see that, but I see your point, too, Elrose (after all The Lay of Leithian was a deliberately stylized version of his own courtship of Edith.) I don't think Tolkien saw himself as storming the gates of hell to recover future stars though. Remember, the chief grudge Denethor (II) held against Faramir was that where his elder brother was a man of action after his fathers heart, Faramir (II) was in many ways "Gandalfs son," scholarly where Boromir (II, technically III) was martial, careful where Boromir was bold, sympathetic where Boromir was resolute, visionary where Boromir was immediate, and aware of risk and temptation where Boromir was aware of opportunity and triumph. Not that either was incapable of the attributes I ascribe to the other, but each brother displayed the primary traits of the other latently, subsequent and as a consequence of his own. Which of these traits reminds us of Tolkien?
We must also bear in mind that both the time of creation and level of development is vastly different in the two works. The Silmarillion is an unfinished epic opus, and one begun in Tolkiens college years, when it is natural to envision oneself as something of the conquering hero, victorious against all odds over all adversity. The Trilogy is something entirely different. If its scale is less than that of the Trilogy, it is far more detailed in its execution, and, most importantly to this discussion, complete. It is also the work of a mature author, begun as he approached his fiftieth year and published in his sixties. It's only natural then that the character with whom the "elder Tolkien" identified is more reflective, more contemplative, than his counterpart for the "younger Tolkien," more vital and adventurous, as youth itself.
So, ultimately, I answer the question "Is Tolkien like Faramir or like Boromir?" the way I like to answer all such: Yes.