Twisted conjugacy and quasi-isometry invariance for generalized solvable   Baumslag-Solitar groups
  We say that a group has property $R_{\infty}$ if any group automorphism has an infinite number of twisted conjugacy classes. Fel'shtyn and Goncalves prove that the solvable Baumslag-Solitar groups BS(1,m) have property $R_{\infty}$. We define a solvable generalization $\Gamma(S)$ of these groups which we show to have property $R_{\infty}$. We then show that property $R_{\infty}$ is geometric for these groups, that is, any group quasi-isometric to $\Gamma(S)$ has property $R_{\infty}$ as well. 
Jennifer Taback and Peter Wong