I prefer glass over acrylic. Those cades look nice but having worked with both I prefer back mounted plumbing vs. Bottom mounted like cade seems to utilize. I also like a nice wood stand vs the MDF panels, but this is all personal preference stuff though, not sure if cade will custom fit your tank differently than the stock 1800...
Look into the fiji cube ext tanks if you haven't already. they come with their proprietary coast to coast type back mounted overflows and have 3, 4, 5, and 6 foot models.