I’m using a D420 and a D350 back up. The only difference is that it’s something new, overall the 420 seems a tiny bit better overall, in the water and I’m hoping it holds the tune longer. The G series can be tuned really hot and with the adjuster can go a long time holding tune well but I’m hoping the 420 will hold longer.You referring to the d420, or something else? What's so great about it over these?