Volume usually also means width and surface (planing) area in modern boards, which in turn (usually) help the effective and efficent use of larger fins ; both factors definitely provide early planing and marginal conditions advantage/s. Especially for lighter riders (who will be overpowered by sail earlier in the gust/s), a gusty conditions combo of slightly more "board" (read : volume and planing area and fin) with a smaller sail can really be a more advantageous (and more fun) option than more sail on a smaller board in the same (gusty) conditions.
Likewise, in gusty (and moreso offshore) conditions, the chop (vs windspeed) doesn't normally develop so badly (relative to filled in wind at the "same" speed, and/or more onshore conditions). Accordingly. the disadvantage of having too much board for the chop arrives later in the range of gusty/offshore conditions than filled in, or more side/onshore conditions.
Likewise, if you really analyse it deeply, often in gusty *marginal* conditions, the gust/s just don't last that critical time to allow the rider to pump the board fully thru to the plane, and the board always seems to be "sticking" (c/w a more filled in wind at the same "speed").
In those gusty *marginal* conditions, carrying the extra volume/area/fin can often be the key advantage to getting the gear planing, and then it just keeps running. Yes, for sure, some guys are pumping and early planing wizards, (and others very legitimately choose and tune not to be.. a very important personal choice) but even the wizards can still struggle when it gets marginal enough. Naklua. Last week.
Cheers ~ Ian
[ Sidebar here is that a skilled sailor won't statistically (numerically) need much more wind to get an iS101/105 planing than (say) iS133 or iS145; but the available power from a wind variance of just 1 or 2 kts in that threshold range is very significant. Worse, when it is gusty, or not clean wind in that range. If you're sailing a lot in that zone, the difference can be everything. ]
I'm into speed and small, but planing slow is always faster - and funner- than not planing