Good Advice
Thanks A and C. I'm still in a quandary - because the rest of my 172 is so simple (no autopilot, no GTN device etc), I still can't see the advantage of the HSI function - effectively I'd just have a DI. Although the weight saving would be nice (but not essential), at the moment I'm just considering just one G5 and a new vacuum DI. And as there is so much work to do just that one, why wouldn't I just go for a new attitude indicator too - then when the King 155 and ILS's become redundant and I need the GTN setup for GPS approaches, I do a complete refit and remortgage the house (or sell my wife?)..........