yep this is exactly the plan :) But actually it will be a good idea to use such a feature only if data access is not evenly distributed across the dataset, otherwise it's simply better to buy more RAM or more servers IMHO.
Another question about the rewrite append only log file strategy. Will that have a possibility for loss data if the filesystem fails to recover from last power off? I mean, if you $rewrite$ a file, there is always a possibility.