It is rather odd, I can't really say why you have had so many issues to be honest. The WF2630/2010/2510 etc use the exact same printing head as the XP2**/3**/4** series even the chip recognition board is the same but with differing firmware to accept either T18/16/29 series ink cartridges. The printing head is the same part number.
The WF7110/7610/2750 do use a slightly different printing head (with the larger amount of black printing nozzles) I did find these a little troublesome on budget sublimation inks but with the Inktec inks they are perfect.
Strange, but as they say, each to their own you stick with whatever works for you :)
Alex