For quite some time I have been a strong proponent of using VMWare for customer development. I used to have 2 or 3 Notes clients in various versions installed on my laptop with a directory pointer per customer linked into my main data directory. A little over a year ago I switched to using VMWare Workstation instead for all development. This setup worked out great for me.
Some customers had their own VMWare images and some customers shared a VMWare image. This also worked out great. Once Notes 8 was released I moved my Notes 7.0.2 installation into a VMWare image with a directory pointer to my "external" Notes data directory. With "external" I mean outside the VMWare image OS. This works out great when running Notes 7.0.2 or earlier outside the VMWare image but once I upgraded to Notes 8 the problems started. I started experiencing database corruption issues of my mail database which I of cause access from both inside and outside VMWare.
After diagnosing these issues I came the conclusion that this kind of setup just isn't supported with Notes 8 part of the mix. Therefore I have split my shared Notes data directory into two parts; a customer part which is accessible from inside VMWare and a production part which is only accessible from Notes 8 outside VMWare. This has solved the database corruption issues.
While sharing directories linked in with directory pointers between running Notes instances has probably never been officially supported it used to work and now doesn't. I just thought I would share.
Afterwards I have changed my setup again and moved completely to VMWare for development. In the new setup I have one or two VMWare images per customer (one for Notes and one for Domino) on an external USB drive with the correct Notes/Domino versions installed. This works great and has really simplified development and testing for customers.