In this regard my opinion is:
It's true that with ppd you have to take care about the speed, 150 - 250kbs its great, for a free user, even more great that you dont have captcha and a page full of ads. If we remember the gold days of filesonic and fileserve (that were the most serious ppds ever ( I mean you seem to got the potential, but we have to wait and see if our needs as uploaders for a second great server are gonna be filled). the speed was that and they got captcha and limitations, and it was not a problem for uploaders making money, i could say my self that at fs i made a really great amount of money (not peanuts like people that makes only 100 in a month or so). The great thing about you is that ATM you really seem to count the downloads in a great way, it's FUNDAMENTAL. PPS is very important to the site, but a filehost withou ppd is careless, because let's face it nobody wants to have 5000 downs in a day and not get a sale (i mean with me that happen, we are bringging great traffic to the site). Speed limit in my opinion is more important then time limit, because the user that can only download 1 file per time will have to wait for the doownload finish, even thou hes got 1GBS net.
If the same user downloads at unlim speed, he will just change the ip (face it, its easy to do). And will for sure compromisse your sales. And its not good even for the ppd guys, because you will pay for the traffic, the uploader, and soon would have to low your rates, wich would cause many uploaders to leave. And that is the big picture, fserve and fsonic became trusteble to us, because the rates were the same always, the count was ok (not 100% with fileserve, but i would give anything to have them back), and they paid always on time. I mean i had more security in receiveing on tuesday from fs, than from my boss every month.
You are doing just fine moogie, keep listenning to your uploaders because now they really need a second trustable ppd filehost (thank god we still have uploaded), if we could still could count on you for the comming months it would be like old times.... for sure
hope that i could help...