V2 vs V4 vs Gansulin vs Xulin pens — worth the extra $$?

Hey research rats, curious what everyone thinks about these pen models. Is there a real difference between V2, V4, Gansulin, and Xulin, or just hype? Do they help with 'the itch' or incremental dosing better? Wondering if any of them are worth shelling out more for. @ anyone who's tried more than one!