[Zope] Site Access Vs VHM

[Pablo Ziliani]

I'm trying to serve multiple sites from a single Zope 2.6.0 instance, so
I need some way to proxy from Apache to Zope (linux).
I've been using a mod_proxy to rewrite urls to i.e.:
http://www.domain.com:8080/clients/clientX, and I placed a SiteRoot
object on each root folder. This model seems to work fine if I don't
have any Zcatalog or (specially dangerous in zope 2.6.0) Xron object: if
so, CatalogAware classes will use the fake absolute_url to recatalog
themselves, raising exceptions like this one:

Module ZPublisher.Publish, line 98, in publish 
Module ZPublisher.mapply, line 88, in mapply 
Module ZPublisher.Publish, line 39, in call_object 
Module OFS.DTMLMethod, line 126, in __call__ 
Module DocumentTemplate.DT_String, line 474, in __call__ 
Module DocumentTemplate.DT_With, line 76, in render 
Module DocumentTemplate.DT_In, line 604, in renderwb 
Module DocumentTemplate.DT_With, line 61, in render 
Module DocumentTemplate.DT_Util, line 201, in eval
__traceback_info__: data_record_id_ 
Module <string>, line 2, in f 
Module Products.ZCatalog.ZCatalog, line 549, in getobject 
Module OFS.Traversable, line 120, in unrestrictedTraverse
__traceback_info__: (['1023215715', 'aereos'], 'app') 
Module OFS.Application, line 108, in __bobo_traverse__ 

So I now wonder if there's any chance to get the same effect by using a
VHM instead. Furthermore, can anybody tell me the difference or benefits
of using one or the other?

TIA, Pablo Ziliani