Hello Gary and welcome to WHRForums!
All users may freely express opinions, impressions, information. However, generally, posting things like "we do offer that", or "we could offer you...", or "we have been providing for years what you're looking for" is not appropriate outside the forums dedicated for advertising.
Other than that you're free to speak your mind and share quality info.
If someone starts a thread asking "Do you have experience with SpamAssasin? Is it any good? What do your customers say about it?", you may share information and say "Our experience with Spam Assasin has been great. We and our customers have been using it for 2 years now and everyone's happy with it."
I hope this answers your question. If not, feel free to ask for more info.
Speaking of rules, you must setup your signature in your profile http://www.whrforums.com/forums/profile.php?mode=editprofile
11. Signatures are allowed, but they must be setup in the user's profile, not manually added to the messages. Signatures can have a maximum of two clickable links, contain two colors, 4 lines (at 1024 resolution), and must present only general information (no pricing details for example). Font size may only be decreased. Signature alignment may not be modified.
It will be appreciated if you could let me know for any specific limitations a hosting company representative has for having to express his views in any of the forums.
I can't really think of any limitations that cannot be applied to the other members as well.