I'll agree with Pericles to a certain extent.
First your numbers are indeed close enough for government work. Second, Tripel is a really cool style, and I wish you success with it.
Third, yeast. There might never be a need to move away from dry yeast. You have just as much control over your beer with dry yeast as you have with liquid. It's a matter of what you like best and what you want your ingredients to do.
Yeast contribute as much as any other ingredient (sometimes more) to the flavor profile of a beer. Belgian styles are famous in that regard - the thing that makes Belgian beers Belgian is the yeast.
That's where dry yeasts generally fall down. There is not (yet) a good dry Belgian yeast except, arguably, Brewferm Blanche. S-33 is certainly not a good substitute. It might be as close as you're going to get in Fermentis's portfolio, but it's still a far, far cry from a true Belgian yeast.
There are a couple dozen excellent liquid Belgian yeasts, however.
For your Pail Ale, S-33 might do nicely. I'd have advised S-05 (American Ale) instead of an English yeast, but that's just me.
"English" flavors are usually taken as subtle fruit, like a hint of Juicyfruit, along with perhaps a touch of butterscotch. Not as fruity and flowery as Belgian ales, and not as "clean" as American ales. If you taste a Fuller's ESB alongside Mendocino Red Tail Ale and Corsendonk, you'll have a start on understanding some of the yeast-imparted flavors.
As to this statement:
It doesn't flocculate well, so make sure you add Irish Moss or gelatin in order to clarify.
Irish Moss will do nothing at all to help yeast settle. Irish Moss is a kettle coagulant which coagulates and precipitates excess malt proteins in the kettle; it is thus a waste of time in most extract beers.
Gelatin in the secondary will help settle yeast. So will patience and time. But, if you're like most new brewers, you can't wait to drink the fruits of your labours, gelatin will speed up the clarification process.