BlobPage Size

Our system run informix 7.22 on a SunSparc 2000 Server running 2.5.1. We are going to be upgrading our disk space over the next 2 years to include up to the 4 terabyte level. I am not sure however what to set our blobpage size to. The size of each image varies from 20k through 100k with no real midpoint and I need to maximize space utilization because our images will add up to at least 3 terabytes eventually. My question : Informix recommends that you set the blobpage size close to the average size of a blob, which in our case is 60k but we have a large number of images that are more than 60k and a large number of images that are less than 60 k, we would be wasting a large amount of space by setting the blobpage size to 30 (2k pages for sun), it seems my only option is to have a small blobpage size around 10-15, which will mean several pages will be required to store one image and increased overhead, but will waste less space. Is this a good approach or are there other options. Also does any one know of a good 3rd party vendor who has a backup capability for a 3-4 terabyte Informix Database. If anyone could help please email me at saabtoo@aol.com. Thanks