If you're just changing one controller for another, it shouldn't make any difference to however your engine
battery gets charged... I don't think. As I said before, my knowledge is basic but I'm pretty sure it's normally a separate gizmo to control and divert
solar power to the engine
battery, not the
solar controller itself. My first 130W
solar had an old pmw controller to deal with the power coming down from the roof and a separate "
battery master" that diverted a bit of power to the engine
battery when needed. My new system has a 245W
solar panel and a lovely MPPT controller that can cope with up to 440W of
solar power if I ever wanted to add another panel. Again, there's a separate gizmo to serve the engine
battery - this time a
Victron Cyrix
battery combiner that lives under the bonnet.
In short, if your Autosleeper system already has a separate gizmo to serve the engine
battery, then wiring it in to a replacement
solar controller shouldn't make any difference to its continued function...
... I could be wrong but it seems logical to me!

C'mon all you experts... let's have a simple explanation.