IRS versus SA
I know that some think that IRS rides better than SA or that IRS handles better. IRS will let the trike lean out in a corner and this lean out, if pushed hard enough, will both increase steering effort as the front tire still leans out with the trike ... and increase the effort required of riders and especially co-riders to hang on. IRS might mean a better ride when applied to a 4 (or more) wheeled vehicle which may not always have all wheels in the same plane …
... but with a three wheeler, you are always riding a wheeled tripod with both IRS or SA and all three wheels will always be in the same plane. I've ridden both, there is no discernable difference in ride quality. When you see a group of pot holes, you still have three tracks under you to steer through them. When that left rear hits a pot hole at 55 mph, you won't feel a difference between IRS or SA.