Big difference between 3.5 and 4gpm?

Considering 2 different machines right now. Looking to specialize in Homes and Decks. Need a machine that is efficient yet works off a standard residential water source. Is the extra .5 gpm worth the additional couple hundred investment? Will be using with an Xjet M5 this season.

.5 gom isn’t enough difference to matter when just washing siding however, if you’re considering a belt drive model verses a direct drive model, that is a HUGE difference.

Thank you for your input, belt drive is a little more than I’m able to invest at the moment but it is indeed in my plans for the not so distant future