Wow, only just found this thread, and as an owner of a 180 Jota and ex-owner of an RGS (and the similar but tuned SFC1000) I feel the need to comment.
It's often said by Laverda buffs that more myths and plain untruths are perpetuated by people who've never ridden them than almost any other make, and this thread sorta fits that view. I thinks it's a product of their rarity, especially in some markets, and their position as one of the most expensive bikes you could buy back then, the two being linked I guess?
180 Jotas WERE the fastest production bike in the world for a time and had the proddy racing success to prove it, mostly in UK and Sweden. Compared to the other powerful bikes at the time (mainly Z900s, everything else was at least 10bhp less) they handled a fair bit better. They were never "terrifying anywhere near their top speed" on the road, and tended to weave predictably on the track at 10/10ths, which was, in fairness, a fair bit faster than most other's 10/10ths. A recent track day on mine (admittedly lighter than stock but otherwise standard frame) never gave me any moments and was a model of stability. I was lapping with Rob North Tridents and hitting 125mph (GPS speedo) on the short straights up to the braking points. On the road compared to my mate's 1000 Multistrada who I ride with, the suspension is woeful (30 years difference so it should be), but the stability in fast (smooth) sweepers is at least comparable.
The RGS was a step up from the 180s with the smoother rubber mounted 120 engines as has been said and a lower CofG, but a 1000cc 180 (2 pistons up, one down) vibrates like a 333cc single not "one and a half bonnevilles", and my own experience of my two bonnevilles bears that out.
Spares are no worse than any other small production 50 year old bike and actually much better than most. Wolfgang, OCT, Redax, Laverda Scozia, Laverda Paradies etc etc are all great sources of spares and expertise. I would put the spares prices and availability at about the same as, well, Guzzi V11 Sports.
Finally the RGS was the original company's swansong and was (and still is amazingly) a superb sports tourer with advanced aerodynamics (only the R100RS could really compare at the time) and like most Laverdas, fabulous build quality (again, for the period) and reliability. A lot of RGSs are still being used for exactly what they were built for.
incidentally, the two colours (red and silver) were due to use of specialist (BMW car bumper derived) flexible paint applied to Bayflex flexible plastic mudguards and sidepanels, which could literally be bent in half without leaving a mark. Possibly a solution looking for a problem but a mark of how seriously the Laverda brothers, who ran the company and were both passionate bikers) viewed their products and strove for quality. Fully adjustable eccentric footrests was another example that is yet to be replicated to this day (god knows why?)
The filler cap at the front was allegedly a response to threatened crash testing being introduced by DoT in the US, which never happened and cost Laverda money it could ill afford. Advantages are easy filling with a tankbag and elimination of the godawful leaking filler cap that all the Italian manufacturers used back then!
If I was asked to ride from here (UK) to say, Sicily on my choice of any 70s or 80s bike I'd choose in order (having owned and toured on all of them):-
Laverda RGS
BMW R100RS
Guzzi Lemans Mk3 (not two up!)
The RGS featured in this thread btw, was an "executive" with purpose made panniers and hand extensions on the fairing, very very rare.
Sorry, I'll get off my high horse now!