TopoGun is a great topology tool and I use it for all of my topology work. I find that TopoGun's toolset allows for quick topo work and the subdivision feature works well. The subdivided mesh can be used to fully recover the intermediate subdivision levels for later use within applications like ZBrush or my personal favorite, Mudbox.
I started using TopoGun when I needed to find a good topology solution for my pipeline. I purchased the Single User License for $100.00, which for me was deal closer. TopoGun's toolset is great for any topo jobs and the price is unbeatable! I'd highly recommend checking it out. There's also an OS X version too.
TopoGun 1.06 RC1: What's new: Numerous bugfixes. Improved user interface . - The floating licensing server is now available as a Windowsservice too (TopoGun License Service), so there is no more need to run the server under a logged-in account. - Right clicking when the Bridgetool is active switches to the SimpleEdittool. - Vertex Conformingis now fully multithreaded, using up to 256 CPUcores. - Border Verticesand Border Edgeson the fly calculus. - The Show Bordersoption in the Optionsmenu, to enable/disable border vertices and edges display. The border vertices and edges display characteristics can be tweaked in the Preferenceswindow. - Antialising for scene elements rendering. This option can be enabled/disabled in the Preferenceswindow. - There are no more Mainor Secondaryvertices and edges, the rendering pipeline and interface have been simplified. - The Preferenceswindow Colorstab was updated, in order to reflect the changes. - The Steady Mousefeature allows you to create smooth mouse paths, with any tool you're using. The option can be enabled/disabled in the Optionsmenu. Currently, its only real use is in conjunction with the - - -- Drawtool, in order to help you draw smooth lines. The Steady Mouse Radiuscan be modified in the Preferenceswindow. - The Reject Inner Facesfeature helps in removing unwanted faces that are created in the interior of three or four sided tube-like meshes. The option can be enabled/disabled in the Optionsmenu. - Implemented a keepalive like command in TopoGun, TopoGun License Service and TopoGun License Server, in order to keep connections alive and not have them lost on timeout by some routers.