For software that uses F-keys extensively - especially with shift/control/alt combinations - having f-keys on the left is hugely easier than awkward top-row-reaching. Plus having a 24 programmable F-keys along the top (MCK-142 Pro mentioned above) is great for long sequences that are only used occasionally (mine are a mix of long 'cd's, mail checks, ssh to various hosts and one to paste links to HN stories into the local wiki).