I too have used the overseas instant hot water systems around the world and found them invariably extremely efficient... and sensible. But basically the Girard is awful, almost everyone hates it, and I specifically ordered my 2019 S-SRT to have the Suburban even though RT had switched to the Girard for all the Promaster models.
I know one who switched to the only Truma model that was a direct switch and it isn't much better. The good Truma choices don't fit.
I too recommend that you have it switched to the Suburban.
2019 Roadtrek Simplicity SRT (almost a Zion)
2015 Roadtrek 170
2011 LTV Libero
2004 GWV Classic Supreme