The Y shape exists for one reason: it gives you two arms to moor between instead of one edge to bump against. Your boat sits in the middle, the kayaks go on the outsides, and nobody is climbing over anything to get ashore.
There are two sizes and they're a long way apart. The 4 metre takes six adults and weighs 23kg, which one person can drag and two can carry. The 8.5 metre takes twelve adults at 42kg, which is a proper waterfront setup rather than something you throw in the boot on a whim.
Both are drop-stitch double wall fabric inflated to 4 or 5 PSI, so they're firm to walk on rather than wobbly. Both pack into a bag with the pump and repair kit, and both live in the shed over winter instead of taking up a mooring.