It all comes down to "typical sailing conditions".
Since I can get at least 60-80+ days a year in planing conditions, I only get on my 1985 Superlight longboard when I race in less than 8 knots. My Formula gear certainly helps with those 8-12 knot days.
If I lived in an area where 75% of my sailing opportunities had winds less than 10 knots, I would no doubt buy a new longboard of some type. If I were a novice and lived where 75% of my sailing opportunities had winds over 10 knots, I would get a board that was easy to learn on, but could also offer "short board" type performance when the wind picked up (Rio?).
Formula 160; iSonic 111; HiFly Move 105; Tiga 263; '85 Mistral Superlight.
Maui Sails TR 11.0; 9.2; 8.4; 7.6; 6.6; Maui Sails Switch 6.0; 5.2; Maui Sails Global 4.5; 4.0.