I own two bikes with Shimano IGH systems, one with an Inter-7 hub with roller brake and the other with an Inter-8 with coaster brake. I use these bikes for a year-round 10 mile R/T commute. I can attest to the fact that the hubs indeed very low maintenance; clean and weather-proof. You can also shift gears at a complete stop. The hubs are a good choice for city/utility bikes or bikes ridden in wet or snowy weather. However, they are heavier and slightly less efficient that a cassette & derailleur system. Another drawback is the IGH wheels are very difficult to remove if you have a flat tire (especially in the dark by the side of the road because you have to keep track of various small nuts, bolts and washers).
For a 20-30 mile R/T commute I would advise you to look for a quality cassette & derailleur system. I think you will be happier with the drive train efficiency and ease of wheel removal. In my mind, IGH hubs are better suited to shorter commutes and city riding in start & stop traffic.
You are on the right track…sometimes it's better to buy a good bike and then add the accessories that you want later on. At a minimum, plan to spend extra $$ on fenders, lights and a good lock(s). I've also found a kickstand to be very helpful for commuting.
I've not ridden the Transfer but I have seen & handled the bike many times (I live 5 minutes from an REI store). The frame & wheels look OK but some of the other components -- stem, crank set, brake set, rack, lights. -- did not seem like they would hold up well to all-season riding. That said, they would probably be fine for most commuters' needs.
As far as I know REI still makes the Randonnee. REI is in the process of switching over to its 2009 bike line so they are likely updating their web pages at the moment. REI's bikes are currently on deep discount and can be a great bargain (if you can find one in your size). Add some fenders to the Safari and you've got yourself a fine mid-distance all-weather commuter bike.