I've used the Wyeast 1388 for about six batches and am going to do another batch with it tomorrow night. I have a batch from two weeks ago I made with this strain, and its still bubbling away (about 1 bubble every 20 seconds) and had high kreusen within 12 hrs of pitching (no starter, just the smack pack). It is a great strain with excellent attenuation, but your beer will be a bit tart for at least four weeks from bottling, though its not too bad. However, if you can wait at least two months, it really mellows and is fantastic!
I've used the 1214 Abbey Ale for several batches, and its good, too. And I did a Dubbel with the Wyeast Trappist strain that turned out very well, but since the ingrediants were very different from the batches fermented with the Abbey yeast, I can't give a valid comparison in taste. However, the Trappist took noticeably longer to carbonate (over four weeks) compared to any of the batches made with the Abbey or the Strong Ale yeasts.