I've been a user of the FXpansion VST-DX adapter for several years. The product, since acquired and marketed by Cakewalk, is really one of those innovative tools that opened up an entire market. For that, I think Angus deserves major kudos.
Is the Cakewalk VST-adapter the best on the market, though? Sorry, but no.
There are many things to like about this product, not the least of which is that it comes free with SONAR. It also is effective at wrappering VST and VSTi plugins, and is remarkably stable. Other thoughtful touches include the ability to randomize the VST parameters, and strong fxb/fxp support.
What the product lacks, however, is effective management of plugins. I don't know about anyone else, but I have hundreds, if not thousands, of VST and VSTi plugins on my computer, and on my laptop. Managing access to these plugins is an absolutely essential feature for me. Unfortunately Cakewalk's VST adapter does not give me the opportunity to rename plugins, nor does it allow me to categorize them by type, manufacturer, or function. If I want to do that, I have to separately run Cakewalk's Plugin Manager - but even then I have to be careful! If I run Cakewalk's VST adapter again, I run the risk of overwriting all my carefully-specified names. Put bluntly, this is a show-stopper problem for me - and is the reason I use Directixer instead.
The Cakewalk VST adapter also lacks the ability to route MIDI *out* of a VST plugin, but honestly I've never felt the need to do that, so I dunno if that's a big deal or not.
Overall, I'm keeping an eye on Cakewalk's VST adapter. If Cakewalk would only adopt a Directixer-style management interface, I would be all over it. Until then, I'll stick with Directixer.