Depends on how good they are, and how much you like to select styles on the fly, I guess.

Personally, I never met a ROM style I couldn't improve. at least mix wise, and don't get me started about the overly loud OTS's (do you all play with feathers? ). So, for me, editing and improving the ROM styles is pretty significant, especially when you consider that to edit it and store it somewhere else firstly isn't as easy to get to in a hurry (I've got 91 pages of styles on my card!) and eats up HD space, while the ROM style sits there uselessly, also taking up space.

If you make UPG's for everything you do, it's not so much the issue, but if you are accompanying someone else, and they need the Sunshine Bossa, I'd rather get it from the ROM section, ready to go (my way!), than have to 'search' for it from the HD or card...

If I ever sell my G70 (perish the thought!) it will be a piece of cake to load back in the factory ROM styles and UPG's for it's next lucky owner (but I'll give him or her my edited ones to compare)...