Some high level thoughts to throw into the mix......
- Why 5m? If it's for a garage be aware most standard trailer drawbars will add a good m to your LOA. Likewise most standard single doors limit you to 2m beam (and be careful of your trailer (axle) choice!) (and having lived with what evolved into the O-Pro 5m / 2m beam for a few years now it's an awesome sea handler (can stay seated and / or hack 25 knots + in the lumpy stuff in relative comfort
), but a tad limited in places to put seats, so it's maybe handy that Mrs 9D is a fair weather sailer!
- What about a phased upgrade? e.g. SR4/30Hp then mothball the 30, buy a 50. Then buy a bigger hull where 50 is at it's lower end of it's useful HP, punt the original setup to fund the big hull. Run the 50 for a while, then repace / PX the engine for a 90..... You get the idea.
Is old bad? What you see in the box to the left of this post is a 1984 hull and an engine that started life in the 70s on a 1960s design...... OK, I like tinkering with stuff like that but the engine is now 1990s spec, and talks NMEA2K to the plotter. Tatty looking doesn't necessarily mean rotten in the commercial rib world, but does come with increased risk / rebuild entertainment!