I went through this process about 5 months ago.
I was finding difficulty justifying the price of of a G25, so I bought a DFP.
They are around £70 in the UK.
It took me approx 4 to 5 days of fairly intensive practice to get up to my previous pad speeds, then I went on to get faster.
The DFP is excellent value for money. However the FFB is gear driven, so you can feel a slight notchiness in the movement.
In any geared drive, there will always be a small amount of backlash. This manifests itself as a small dead zone at centre steering. Whether this is a true dead zone regarding the actual steering inputs, I could never actually tell, so it probably isn't.
When time trialling with the Lotus 111R on the London reverse course, there is one particular part of the course which required complete accuracy - it's a fast left/right flick which has walls either side. Particularly here the backlash was extremely annoying, and it felt like it was really making this part of the course difficult.
This was when I decided that I would upgrade to the G25. The G25 is better in every way.
It took me 5 laps of Suzuka to beat my DFP times.
I can appreciate that not everyone is in the position to blow £160 or so on a wheel, so for this reason I would say that if all you can afford at the moment is a DFP, then go for it. It will give you a much better gaming experience than the pad.
When you're done with it, sell it on EBay and get more than half you're money back. Maybe when you can afford the G25 👍