I'm for 1.5x or 2x scroll drop rates. Here are my reasoning's:
1) It allows for players to feel rewarded for their training efforts. I started playing Maple on release of Bera, and I can recount most of the scroll drops, because they were THAT infrequent. It sucked.
2) As a private server, we will have an order of magnitude less people than the original server playing, thereby decreasing the amount of scrolls present in the economy, and sky rocketing prices. This will be off putting to new comers, casuals, and semi-casual players alike.
3) Being able to be okay with hitting a portion of scrolls, because you can go and hunt them, or afford to buy more, is nice. Its not nice to be unable to purchase no other scrolls after a scrolling when 2 or 3 failed.
Those are all feeling points. The statistical math is a bit more complicated, but after work I'll try and put together some numbers for you folks. I saw some posters put together some rough numbers, but I think the math is a bit more complicated (I'm an engineer, and while its been about 8 years since my statistics college course, I recall it being less straight forward). I'll do some research, and report back.
Edit: I did the research. Its not that straight forward, and I finished work kind of late today (working from home...just means I work all the time now! lol) Basically, its a little more likely than how we looked at it, but not by MUCH.