Logarithmic and/or linear scale sliders when to use them

I've been having a discussion with someone at work regarding the usage of Logarithmic and linear scale sliders. Here is an example in a jsfiddle*.

Background of the problem

We are currently building something that allows consumers to compare sim only plans. In Holland you have data plans that can range from 250 MB to an unlimited data plan.

I've made a quick example on how the slider is used, the user can slide to select a minimum amount of data/min. The largest option before 'Unlimited' (in the example 'Onbeperkt') is 20.000 MB.

Discussion

The discussion revolves around what scale we should use. I say a Logarithmic scale else user needs to drag a lot before the 'average' data plan can be selected (the amount between each step increases, so first it is a step of 250 MB -> 500 MB and later it turns to 1000 MB and 5000 MB).

The developer believes using a linear scale is better, with a step of 500 MB. His reasoning is that a logarithmic scale defeats the whole purpose of a slider. I do understand his reasoning, I however find a logarithmic scale to work better as it reduces the amount of steps.

My question

Is there a rule of thumb or a general principle regarding the use of linear/logarithmic scaled sliders.

Extra information

As asked in the comment of John, it in our live version it is indeed not possible to select 3452. We are using 'steps' already, for lack of a better word I used linear and logarithmic. I mean that at the linear slider the steps remain 500 and at the 'logarithmic' slider the step size increases as the value gets higher (initial 250 and later it becomes steps of 500, 1000 and 5000).

Translation to English

• Belbundel = Amount of minutes
• Databundel = Dataplan
• Onbeperkt = Unlimited

*The fiddle works on my computer, but that can be because of cookies. So if the fiddle does not work, I use the bootstrap slider of seiyria. Examples 1 and 15 show linear and logarithmic respectively.