This one is a bit tricky because the dps differences you'll see are really showing the item level differences of not only the tier itself but of the gear that usually would accompany your tier pieces.
For a piece by piece comparison, you might try the per slot breakdowns on EJ:
Helm: http://forums.elitistjerks.com/topic...1#entry2278369
Shoulders: http://forums.elitistjerks.com/topic...1#entry2278372
Chest: http://forums.elitistjerks.com/topic...0#entry2278365
Gloves: http://forums.elitistjerks.com/topic...1#entry2278368
Legs: http://forums.elitistjerks.com/topic...1#entry2278370
It can be a bit much to absorb, but this can help you figure out if it is worth, for instance, trying to roll a coin for a heroic over normal or HWF over a regular heroic.
As for general statements about the gaps between N->H and H->M, I've noticed that the leaps are often 1-2k dps for each direct upgrade for these item levels. Again, you can take a look at the above lists for closer approximations. Some tier upgrade pieces are worth more than others, depending on the gear you have (i.e., if you are lower on crit, a crit-heavy piece like the tier legs can be a huge upgrade).
If you want to see the kind of dps increases you are likely going to see by going from a Heroic raider to a Mythic raider, you can see this kind of comparison on the main EJ aggregated guide here (http://forums.elitistjerks.com/topic...nter-guide-62/) in the Heroic vs Mythic gear breakdowns. However, I haven't really done a Normal breakdown, partly because the existence of crafted and BoEs (which can reach upwards of 731 ilvl) obtainable through crafting and AH make the "Normal" profile really sketchy to nail down an example set. The truth is a "normal" raider who only does normals can be well over 700 ilvl without even setting foot in heroic HFC raids (especially if you factor in raiding the old Mythic BRFs to gain filler gear, which is doable now without even really having a full Mythic raid after nerfs, having a few heroic-geared HFC friends and whatnot).