After reading all the problems and issues on the Promise card, not to mention the horrible write speeds. There is no question that you should pay a few more dollars for the Areca controllers. Well worth the headaches it will save you and definetly give you better write speeds. The Areca ARC-Series has been out for over a year, Since then the company I work for has switched over from 3ware to an all Areca storage server line, We have had no major issues, except for some motherboard compatiblities, which was quickly solved by a motherboard BIOS update.
The way I see it, Areca has some outstanding RAID controllers. They were the first company to offer SATA II 3Gb/s Controllers in both PCI-X and PCIe interfaces. Promise and 3ware are just finally releasing their controllers while Areca has allready been there done that. Areca has even dropped in price down to an affordable level (compared to the original prices) Just pay the extra money, It's well worth it.