I have a bunch of Lu + Gugrusaurus data as well. Think I had the same thing for Lu + Lik, but doesn't look like it got backed up. Ah well.
A lot of it is in a text document and isn't pretty to look at, so I'll have to organize it later. Maybe tomorrow night.
In the meantime, I do have a very small sample of 12 boat trips that I put into an excel file, so it's all nice and organized.
Total Bites: 45
----------------
Catch: 16 (35.6%)
Line snap: 19 (42.2%)
Rod Break: 7 (15.6%)
Lack of skill: 1 (2.2%)
Ran out of time: 2 (4.4%)
Edit: Hey! A picture! Why not!
http://imgur.com/egYkM.jpg
This was all during a full moon. This was also 2009, and was pre-moglification; just 100 fishing skill, fishing skill+ gear, and maybe advanced support if I used it. Had my brother's character logged on and on /follow to repair my rod.
Other than the "ran out of time" bites (the numbers of which will differ according to how easy of a time you have with gugrus), I think those % are roughly what you'd expect. Again, I'll parse all the other data I have at a later time and see if that's true.
Also, taking just the small sample given, that's an average of 4 gugrus per hour. At the time, gugrus were 20k a piece, so "making" 80k an hour (in the sense I didn't have to buy them) for me was worth it. Again, this is 2009, so potential to make money, and ebisu fish prices, have likely changed, and your mileage may vary.
Edit: And yeah, I understand the discouragement that goes with this. Looking at the average gugrus per hour after the fact is nice, but in the midst of fishing it can be a drag when you get boat trips with no bites, all line breaks, etc. It's nice when those are offset with all catches, though, as rare as they are!
Edit 2: If I'm feeling particularly spunky, I could include more detailed Ebisu + gugru numbers, and figure out the average haul per hour. The numbers I gave earlier would average to 8 catches an hour, or double that of using a lu shangs. I'm not sure if this is an accurate representation, or if I simply had a good day that day, so it might be worth checking.