I can't report on the curves per se...what I can give you is that the BF40 produces 43.8 ft-lbs of torque at 3500 rpm and the BF50 produces 47.1 ft-lbs at 4500 rpm. Given the wide spread (1000 rpm) between the peak torque rpms and the relatively small difference (3.3 ft-lbs) to start with it seems reasonable to expect that they're not very far apart at 3500 rpm (and it wouldn't suprise to find the BF50 slightly lower at that point). At any rate it's splitting hairs; the real world differences wouldn't be discernable in most cases. It's really a matter of horses for courses; it doesn't appear to me that there's any indication that the BF50's will outperform the BF40's in the rpm range where most CD22's spend thier time (with twin 40's in the 3500-4000 range). There is clear evidence that if you routinely run in the mid-4,000 range and up that the BF50 is a better choice (which is why it works best for CD16's and such). Also, the BF50's WOT (wide open throttle) range should be 5500-6000 (max hp at 5750); the BF40's 5000-6000 (a good indication that a BF50 shouldn't be "lugged"); it's max hp comes at 5750 rpm. This translates into being able to prop the BF40 a bit more aggressively and given the same 2.08:1 lower unit gear ratio on both the BF40's and BF50's, the BF40's should perform a skosh better in the lower rpm ranges (at least up to the low-4,000 rom range where the BF50 starts "to do it's thing"). The final decision usually involves the money difference (about $1400 at MSRP); whether or not the extra dollars spent translates to a good return on investment depends an awfully lot on where and how you run the boat and on what makes you smile. I usually opt for the less expensive option given that most CD22's in our area will not be operating in the range where the BF50's extra performance comes into play. Seat-of-the-pants operations validates the numbers.
The BF135/BF150 question is more easily answered since there is a lot more than minor information available. Here we do have published torque and horsepower curves and there is a lot of information in the new Honda Sales Brochure. The motors are also in stock now at many dealerships.
Peak torque on the BF135 comes at 4500 rpm @ 140.9 ft-lbs and the BF150 at 5,000 rpm with 145 ft-lbs. The torque curves closely mirror each other up to 4,000 rpm where the BF150 takes a dip and they're almost equal. This continues through 4,500 rpm where the BF150 changes over to VTEC and its torque starts to climb away from the BF135 (who's torque stays flat here); the BF135 then falls off pretty rapidly after 5,000 rpm. The BF150 falls off a bit after 5,000 but it's a very gradual decline. The horsepower curves are very, very close; in fact they cross at 3500 rpm. At 4,500 rpm they're almost together and don't really start to split apart until 5,000 rpm where the BF150 stays on it's linear path and the BF135 drops off from it's peak at 5,500 rpm. The peak on the BF150 is really at 6,000 with 160 hp; 150 hp at 5,500 rpm.
My assessment is that I'd be perfectly happy with a BF135 on a CD25; actually I'm very happy with the BF130 on the CD25. The BF135 looks great in comparison to the BF130's torque curve; the BF135 holds about 140 ft-lbs from 3,500 to 5,000 rpm (very flat!) whereas the BF130 is just over 120 ft-lbs at 3,500 with a steady linear increase to around 135 ft-lbs at 4,500 at which point it drops sharply. The BF135 hangs in there pretty well for another 500 rpm (to 5,000) and then drops quickly like the BF130.
Given the $1600 difference (at retail) between the BF135 and BF150 the BF135 looks like the better choice (especially given the torque and horsepower is all but the same from 3,500 to 4,500 rpm) unless you've just got to have the top end (on a C-Dory!?!).
And congrats on your "soon to be a C-Dory owner" status.