The 442s offer a pretty luxurious 1st-class specification (well, it looks like that to me) and I seem to remember Southern making a bit of a song and dance about it when introduced. They'd be pretty foolish to downgrade that to 377/6 standard. Well, unless the management have seen the grief that SWT get from the Haslemere brigade about 450s and fancy some of that action themselves.
I'll be interested to see if they can spec the luggage carrying properly, though. Currently, on a 442, specifically refurbished for airport work, no-one can see their own suitcase. Furthermore, a 442 will take a reasonably-sized bag overhead, which is something the roof-line on an Electrostar prevents.