Let's start with the basics:
Why do people want a DKP system?
They feel they are not rewarded for their effort, while others benefit from their effort
Who wants/doesn't want a DKP system?
The people that put in a lot of effort

Advantages of DKP system
People are more likely to get rewarded based on the effort they put in
Disadvantages of DKP (this is where it starts)
- If you miss out on 1 or 2 raids, while your 'competitors' don't, you move down the line in points, and you will most likely have to wait for these other people to get their item first, assuming you all want an item that drops quite often.
- Items that don't drop so often...people with the most points (even though they only have 1% more than the #2) will win this...and the #2 can wait 2 years until it drops again.
- Administration....have fun calculating points for 50+ people. Have to roll anyway on the first couple of raids, lot of argument about point distribution too.
- Demotivating for new players the first couple of raids if their class has a lot of people active.
- Pickup people...do they have DKP points?!
Ofcourse, the fairest thing is if people get rewarded for their effort evenly, but this is very hard to realize in practice. So basically there are 2 'groups' (someone already posted this, forgot who, too lazy to read it again): people above the effort/reward line (more effort, less reward), and people under the effort/reward line (less effort, more reward)
I also do realize that the system needs to change so that people get rewarded more equally to their effort, but the disadvantages of DKP scare a lot of people.
The Tier System
This system is used quite a lot as well in other games, have used it before as well myself. It basically means all players in every class are divided into 'ranks' called tiers. These tiers are based on activity in PvE raids (or whatever you want to base them on). When an item drops, the master looter picks it up, and then everyone that is allowed to can roll on it....with a small change.
People that are in tier 1 (lots of effort put in) do /random 100 for example
People in tier 2, that put in a little less effort, do /random 90. This means that people in tier 1 are more likely to get it, but people in tier 2 aren't without chance!
Let's compare it to the disadvantages of DKP, using a Shaman example:
- Missing a raid once or twice....ok you might move down a tier, or maybe you won't even move down, based on the tier-rules you set. But even if you do, you still have a chance to win the item, but just less chance than someone who DID attend all raids. Let's say a mob drops Shaman leggings everytime....4 regular Shamans, 3 who attended all raids, 1 who attended all but one raid. This Shaman has to wait until the other 3 get their item most likely according to DKP, and this will perhaps demotivate him to come on the next 3 raids if there are no 4th, 5th, 6th Shaman that are close to him in points anyway. With the tier-system, this Shaman has a chance of winning anyway. If an item drops really often, then the tier-system doesn't differ much from the DKP system though, because everyone will get their item in time.
- Items that don't drop so often...this is where the difference between DKP is notable. Imagine we all eat superpower bananas and on our next MC raid we happen to defeat Ragnaros. The power fades and we won't be able to kill him for another 5 years. He drops Uber Shaman Chestpiece of Overpoweredness. Our poor Shaman that only missed 1 raid won't get this item, because 3 other Shamans didn't go on vacation when he did. With the tier system, even if he is in a lower tier, he gets a chance to roll and win, albeit a smaller chance. The others get to /random 100, but he gets to /random 90 at least and get a shot at it.
- This also kind of fixes the problem of demotivation for new players. The new players have to earn lot of points first before they can win an item. With the tier-system at least they get a shot every raid at an item. And even if they win, it won't upset the other regulars hopefully, since there is a small chance, and this guy has it now, and next time they will get it again. The chance of another new guy coming in and snatching it again on the next raid is very low anyway.
- Administration....don't have to keep track of individual points earned and spent etc. Just have to keep track of the tier a player belongs to.
- Pickup people...just make a special tier for them and warn them in advance about their chances of winning. Also it makes more sense that they have a smaller chance of winning....after all it is OUR raid and THEY get invited. If they don't agree, WE can always find someone else...THEY can't find another MC raid that just happens to be on

This system is flexible too....we can decide for ourselves the rules of this system, for example when someone moves up or down a tier. Or what /random every tier gets. Maybe you only want to use 4 tiers of /random 70 80 90 and 100. Or perhaps we think 10 tiers is better of /random 100 95 90 85 etc. etc. Can even say that for some items like Uber Shaman Chestpiece of Overpoweredness you need a minimum tier.
Yes I know there is still a factor of chance involved here, and I know that (particularly the more active) people want security in their MMORPG-life, but it solves a lot of problems imo, and we all know it's fun to roll anyway

Feedback please!