I didn't "need" the Sabre early in the vanilla campaign, I simply came across it and bought it. I was just saying, it was lucky that I did buy it back then because it would be tiresome and tedious having to travel around without fully functional nav system during the Crossfire campaign in order to make money, make friends with the right factions and so on in order to get a sufficient ship for the CF campaign.
I guess I'm generally somewhat disappointed in the way the CF campaign doesn't give you a break, because the "beefing up" your ship and firepower and then applying it to storyline battle is an integral, fundemental part of the game's mechanic.
It's almost a moot point now, because I've run into the same Sol crash issue as so many other people. (Tried deleting autosave, going back to mission savegames etc, to no avail.)
I wish CF would at least give me the full nav functionality when I want it so that I could freely explore and leave the campaign. Maybe I'll try Open SP instead.