Ecco alcune cose da prendere in considerazione nel scegliere se usare TFS con gli account Workgroup o di Domino:
You can install Team Foundation Server using one of two deployment
models: single-server (application and data tier on the same
computer) or dual-server (application and data tier on separate
computers). In a single-server deployment, you have the option of installing
Team Foundation Server using domain accounts or local workgroup
accounts; however, in a dual-server, you must always use domain
accounts.
If you choose to install Team Foundation Server
using workgroup accounts, you are limited to adding workgroup accounts as
users when using Team Foundation Server. That is to say, you cannot add domain
user accounts to Team Foundation Server that is using workgroup user accounts
to run its services. The reason is fundamental; a service that is using a
local workgroup user account logon cannot access a domain controller to
authenticate a domain user account.
On a side note, you cannot use accounts with blank
passwords as Team Foundation Server service logon
accounts.
Source: Team Foundation Server, Domains & Workgroups