I'm not against a vendor standing behind their product, certainly they all should, but the problem is that most customers won't know for sure if they made a wise SAN purchase for six months or so. It can take that long to get production applications going full steam. SAN storage is installed deeply into the SAN infrastructure. Inserting a new storage system into it takes planning and forethought and removing a storage system may take even more planning and effort.
Let's say you take this vendor up on their offer. In 30 days you have to install the storage system, move data onto it, test it, then move production data onto it, test that, then start moving live production data and servers to it. While storage systems have become simpler and SANs are easier to manage, that's a lot to accomplish in any level of scale no matter what type of storage you have (SAN, NAS or DAS).
Reality is that you are going to live with the storage decision you make, returning it is not an option and I doubt most customers would see this as a difference maker in storage selection. Most storage vendors are going to back their solutions up with some sort of right of return, which usually translates into doing whatever it takes to get your system functional.
In general, installs go one of two ways. One is very smooth from start to finish (a lot of this has to do with the technology selected), or you have an extremely bumpy, tense install from start to finish (the result of weaker technology and poor planning). The difference between the two scenarios is that when things go smoothly you feel confident in the system and you deploy more projects on it. That's good for you and the vendor. When things go bumpy and a lot of extra effort is expended just to get the initial phase complete, confidence is lost and not many more projects go on the system.