It is important to specify that the Intel SSD is one of the best hard drives you can buy as it is probably the SSD with the most complete longevity testing. Thus far, the testing has shown nothing but great things. It is however, considerably slower than most other SSD's currently on the market.
Financially speaking, it is a toss up unless, as stated, you can return the Intel or perhaps you have a computer you use less which you want to store the boot-able files on.
Performance wise, maybe as the OWC has write speeds almost 3 times that of the Intel although even the Intel, which is one of the slowest SSD's currently on the market (it is about to be updated), blows away even the fastest of HDD's that will fit in the MBP, and so the difference between specific SSD's may very well not be noticed by the 'butt-benchmark'. Now over time, yes, you should (theoretically) notice a dramatic difference as the OWC has a better infrastructure to maintain performance. The 80gb was a bit small for my needs and the 120 GB was (for me) enough to put all my primary information on and still have about 40 GB of free space. If a larger size SSD will allow you to have all of your files on a single drive and make life more convenient, then yes, replacing the Intel with a OWC of larger capacity may be worth it.
While the OWC has better wear leveling technology, both of the drives are in excess of 2 million hours MTBF and they will both take a boat load of time for the overstated issues of wear to become problematic. Based on the studies by Intel, which examined wear via accelerated and extended tests (Intel has had SSD's for a long time), by the time the capacity of your SSD has fallen to the point of not being able to use it, the size and even type of hard drive will be long obsolete and obviously will therefore be replaced. In theory, the OWC will maintain performance over time better than the Intel, but how big of a difference will only be shown in time.
I have doubts about the newer SSD's going down all that much in price yet simply because SSD's are still far and away from main-stream technology and therefore they will have higher production costs.