good luck with Watchguard, they are at the same level as linux based firewalls.
They are a company that :
will decide that your FW is no longer a supported product will make so you are forced buy the upgrade hardware.
will not allow the trade of their products second hand and if you get one you must immediately upgrade it to their latest product.
A company that makes the resale and re-installation of the system difficult by using license keys to activate hardware.
From first hand experience and other telcos, it should not be used in critical/telco environment, as they crash, and often wipe the flash card
They are not fun to reinstall and rebuild after they crash.
Having said all that, for years they have had the best management interface which will get you and most managers to sign on the dotted line.