10 hour service?
Well, you dont' have your type PWC listed and it's not in your public profile, so I'll just go generic here. The only thing I'm pretty sure of here, is that your PWC is new.
You may want to check/read your warranty information really good, because in you doing that service yourself, they may void engine damage in the future.
The biggest reason they want that ski back in after 10 hours is to see the condition of the oil. Are there any "shavings" in it? Does it have a milky color? etc....to make sure the engine isn't about to have some type major problem. Just because it's new, doesn't mean it can't have a defect.
If you don't and if your 4-TEC (I'll assume you have the 4-TEC, since its used in the majority of skis now) has a bearing lock up or a supercharger failure, I can tell you the first thing there going to say is "hey, we don't have a record of you coming in for your 10 hour inspection"! So, your screwed.
The 10 hour service isn't all about the oil change, it's about checking the health of your engine. And with these 4-TEC's being as highly sophisticated as they are, I'd bite the bullet and pay them their money. When your under warranty, cross your "t's" and dot your "i's" cause like any company, if they can find a way of cutting their loses due to your fault, uh, they will.
BTW.....I'm a stickler for any kind of repair shop. I'm a pessimist who isn't very trusting of their loyalty to their customer. Would never take my engine to them, unless it was brand new and I didn't want to lose my "freebie" engine replacement if something happened.
Good luck!...........and welcome to the world of fast skis! :cheers: