When new, they will have slightly better damping characteristics when not running them hard. When run hard, like over chatter bumps, they will heat up less and not fade. The extra heat without reservoirs has a compounding effect. I am told that the time before the oil needs replacing is about 4 times as long with reservoirs. When the oil degrades, the metal parts wear faster. They can be added later, but will cost more. Part of that is because they need an oil and nitrogen change when done. You could probably wait a year then have the reservoirs put on.