Pure and Walter's are both great routines. Per my experiences with each of them while using VMWare (yours may vary):
(Un)Pure + VMWare:
It's impressively fast, with optimal rotations and no pauses between 1 hop kills. Invariably, though, after a short period of time the bot will stop functioning while the log fills with dictionary errors, also at an impressively fast pace. This means that every fifteen minutes, on average, I have at least one bot to fix, which involves closing BW via the task manager (it locks up and has to be forced to close) and then ending the still active session online. I've tried stripping almost every conditional from the class code of the two builds I use (simply leaving the bot to attempt casting abilities in priority order), as well as removing the AoE call completely, and while this produces less log errors, the inevitable dictionary error crashes still occur.
Walter's + VMWare:
Walter's is fast as well, but I would guess it grinds about 10-20% slower than UnPure because it pauses briefly between single hop kills. On the flip side, the average lifespan of a Walter's session can usually be measured in hours as opposed to minutes, sometimes running all night on multiple bots without issue. When the bot does stop functioning, it can still be closed without crashing, which means the session is also ended properly so that I can just restart the bot without issue.
In a more perfect world, those Pure errors would be resolved (most of which are on BW's end), and/or Walter's would become even faster by avoiding those pauses. For now, I use Walter's because the downtime I experience with UnPure > the impressive speed increase I experience while it's working. If you do try Walter's, let us know if that at least resolves your multiple bot issue.
Cheers,
-D