Hi and welcome to ET!
If the only problem you have is in your office, but reception in all other areas is satisfactory you have to decide how important that is to make you walk away. You didn't mention issues with reception anywhere else, so perhaps your Treo just doesn't want to be at work!
Yes, there will be differences between phones and it is certainly possible you get reception in spots the other people do not.
You have to ask yourself what is important to you and your situation and act accordingly.
Personally, having recently moved to the BB platform from a 650, I have found the BB to be far superior as a phone just about everywhere I use it, home, the office and "around". I was never impressed with the Treo as a stellar phone, but I weighed and balanced all the other things it did well and I found it to be tolerable. The BB is fabulous as a push-email device too, but it is sorely lacking in polish, and feature-rich programs. Many are spartan and will get the job done, but without flair and style. I truly miss the Palm calendar program. We are still waiting for the Docs-To-Go BB version that will allow editing and SD card storage of emailed doc and xls files. Right now I can view, but nothing else.
Oh sure, it also helped that my company pays for it and they moved to the BB.
You wrote:
"..but they may just want me to buy a new phone"...
I am shocked you would say that (NOT). If you are happy with all that Treos are capable of, and that is a lot, perhaps you should give it a try and see if it works for you.
No matter what you decide to go with, make sure you are aware of the trial period and what is a valid reason to return if, for example, it is for a reception issue and not due to hardware issues. I don't know if they make a distinction and most of all......It doesn't matter what the happy salespeople tell you. CHECK THE CONTRACT FOR WHAT IS IN WRITING.
Let us all know what you do,
SteveTaz