Everybody beat me to it. As Allen pointed out, there are too many variables for anyone to claim: pool surface X will last Y years. Water chemistry is the single largest factor. You can ruin a plaster pool in a few years (or even a few months!). You can stretch the life of plaster out for decades with proper care. Installation is also a huge factor (so your PB's worker's warning about early plaster failure does not instill a lot of confidence in his skill!). The numbers I found when trying to decide indicated that pebble would outlast plaster, perhaps as much as 5-15 years. I have no idea on what those "facts" are based on. That seems to be a common consensus.
Nothing feels as nice as plaster. That's a given. The bigger the pebbles, the less comfortable it's going to be. Also a given.
All that said, I selected a small pebble based strictly on longevity. That's what I was told at the time, and what I still believe. In my mind: a rock is going to last longer than plaster, and pebble finishes present more rock to the water than they do plaster. Check back in 30 years and I'll let you know how I did! (That's the lifespan I need to get out of my pool, or I'll have to replaster again!!)
I'm only half joking about that. I included my lifespan in my calculations. How long do you plan to live in the house with your pool? Will you move in 5, 10, 20, 30 years? Is this your "forever house?" If so, how long do you think you have left? Got any heirs? Do you care if they have to deal with replastering your pool? I know that sounds crazy, but if we're talkin' longevity, those are factors to consider. If you think you'll stay in your house no longer than 5-10 years, get plaster and take care of it with what you learn here about TFPC. You won't have to pay for another replaster. I'm in my forever house. In 30 years I'll either be gone or too old to swim. 30 years would have meant two plaster jobs (the first one, and the next one in 15-20 years). In 20 years, plaster will be twice as much as it is now, at least. So I'm gambling on my pebble lasting 25-30 years, including taking extremely good care of it (which I am). That is a stretch, but with TFP I think I can get close. When my daughter inherits the house, the pool will be her problem. If you think you'll move (or otherwise leave the house) in 15 years, I'd guess that's about the threshold for re-plastering (assuming you take great care of it). More than 15? Get pebble.
I'm also not worried about resale, should my plans change. Some do, when they select a finish. I wouldn't. In my neighborhood (in most neighborhoods), a pool does not add any resale value. Sometimes it can actually make selling more difficult, as many buyers do not want a pool. So it'd be bad enough I'm gonna give a free pool to the next owner, I'm not going to worry about what pool finish he's gonna get, too! He's not going to pay you anymore for the house based on which finish you select, that's for sure. Matter of fact, I got this pool free from the previous owner (proven by the comps of surrounding non-pool homes). My pool was about four years old at the time. The plaster was already ruined by the pool guy, who didn't know how to take care of a pool properly. So I got pebble, and I'm hoping for the best.