I believe you nailed it here when you said:
That being said, the common usage of the term "Reformed" these days seems to denote at the basic level a Calvinistic soteriology and a commitment to the five solas.
But I would add a few more. Reformed Baptists as well as other Reformed believers believe in what is referred as Semper Reformanda (sorry if I blew that name) or always reforming.
Reformed Baptists also believe in all the law, as opposed to say others Calvinist Baptist groups like Sovereign Grace Baptists who for the most part believe that the 4th commandment no longer applies.
Boanerges provided an excellent article on these points in his post, if you haven’t read it I would recommend that you do.
Personally in my opinion, those who insist that non paedo-Baptists or for that matter non-credo-Baptists who claim that the other side aren't really "reformed" are being rather nitpicky.