Rod,
I have this same machine and, depending on what you are planning to do, I would highly recommend getting this option. Pulsing allows you more control when welding thin gauge material. It also "provides deeper penetration and greater depth-to-width ratio than steady GTA welding of the same heat input value" (taken directly from GTAW, James F. Lincoln Arc Welding Foundation).
Since it is considered a "field-installed" option, it can be ordered later but unless you want to take the machine back to the shop, I would order it with the machine and have the boys install it for you. Usually they will do it for free when you buy a machine like that. The guys at my shop did.
$250 is only the msrp, you should be able to get it for a little cheaper as I paid $225 for mine.
All in all, it will make you and your machine capable of doing more for a modest cost.
Best regards,
Kevin