Owen, I don’t think they’ve had White-faced Petrel for a while. Tey are possible but rare. Don't think they have had any since I have been watching their blog in June or July. Have a look at their blog.A Windbirds pelagic has been on my bucket list for a while now, but the 3-day list for a not-inconsiderable outlay is not that impressive TBH. The Pterodroma petrels and high chance of Zino's is obviously a big draw, but for storm-petrels and the commoner shearwaters I've had much more bird-rich experiences in a couple of hours off Sagres for considerably less cash.
As Ken says though, the chance of a white-faced storm-petrel still makes it an attractive proposition, but your trip report emphasises how good the catamaran trip can be. Multiple Bulwer's plus beer compares very favourably!
I’m going on a 2-night cruise in September with Lanzarote Pelagics for about the same cost as the 3-day Windbirds package, at least 60% chance of getting WF Petrel.
Maybe the Windbirds ribs are better in some respects than catamarans, more eyes etc. but I wonder how many sightings of gadfly petrels you might get on a VMT Madeira catamaran cruise with a team of birders rather than one notoriously dosey, dopey, half-awake birder like me. Of course if they find a gadfly on the water, they will stop whereas the catamaran won’t. But I was more than satisfied with the multiple views I got over 2 trips. Mostly views were fly-bys but 2 of the 17 birds were sat on the water, over the 2 catamaran trips. I think most of the gadflys seen on Windbirds are also fly-bys, maybe they chase them to get closer though.
Ventura do Mar sailing boat should be back sailing soon as a day-trip alternative, and Bonita do Madeira too - both offer sailing day trips to Desertas with facilities for 80 euros.