So do you think they are worth the expense? Right now I am planning on installing them in my boat while I have the engines out and switching everything to SCXs.

They are likely worth it. I have run them on my Cigarette 42 Tiger for 4 or 5 seasons now the last 3 with 950 horsepower. I have had IMCO scx drives with shortmaster lowers the entire time. The main factor in if you need them or not is how you drive your boat. If you are doing poker runs all the time and flying out of the water often then they are likely a good investment. If you rarely fly the boat and take it easier than you will see less of a gain. For me they have been good and bad. We haven't broken a drive with them which is definitely a plus. Although we have broken 3 drive guardians in the 4 or 5 years I've had them. The first failure was either the first or second time season with them, at this time I had 800 horsepower a side. We were accelerating and the clutch pack just started slipping and tore itself apart. We think that the reason for the failure was that Drive Guardian had packed the clutches incorrectly, they did them to a lower horsepower than we actually had. So as long as you get them probably packed for your horsepower and torque you should be fine. The second failure happened this season. We were rolling into the throttles and then the splines inside the drive guardian completely let go, leaving us with one motor to idle home on. This was likely due to us running too much power through their older-weaker coupler, since then we installed their new hardened steel coupler and had no issues with it. The final failure also happened this season but was not the fault of the Drive Guardian at all. We broke a bell housing on the back of the engine causing the motor to tilt backwards and rip the Drive Guardian in half. Throughout this process the owner of Drive Guardian has been very helpful. For instance with the last failure he installed a new billet housing, repacked the clutches, and had it back to our shop in 3 days. Moral of the story is if you drive the boat hard they are worth it, just set them up properly with the best parts from the start, making sure the supporting components are all good, and you shouldn't have too much trouble.

Andrew-

I do not baby my boat, big Lake Michigan water and poker runs is how the boat will be used, So with that said, I'll be sticking with my plan to install Drive Guardians. Last season I babied the boat due to it having XRs on it. Drove me nuts, that I couldn't run the boat as it is capable of running. While tearing everything apart this fall, I found a twisted shaft in the bell housing driveline adaptor. That was the sign for me, that I should install Drive Guardians. Thanks for the info!

I have used them for 30 easy hours and broke one of the Drive Guardians and two drives. The drive input shaft twisted in the Drive Guardian splines and I had the pleasure cutting the input shaft with a sawzall so I could remove the drive. They were calibrated prior to installation. They have cost me time and money and I have realized no discernible benefit. Your results may vary....
They look really cool though.

This season after breaking in my new ADS stage 4 drive (xr) with the GD, I ran the hell out of mine.
If your boat comes out of the water ever, its a good investment. IMO Or if you run hard.
My cat hates water, loves to be in the air and after one season its already saved my new re-built (ADS) drive.
Im was at 650 HP, but they are set to your power. Not just a one size fits all.
Sending mine in once I have the dyno sheet (from rebuild in progress) to be re-set.
I called DG for the cost and its under $200.00 to re-set.
There are other threads with race teams that swear by them.
Im sold on DG!
Time will tell on the new drive & DG, but this will be my last XR set up. If it lasts great, other wise I would love to know how your SCX's hold up.

i like reading about the average boaters experience with them. I don’t put a lot of credit in the race teams as many were given a substantial discount on the units, which is great for r&d, and for the teams to experiment but it’s not like they’re going to come out and say “yeah there no better save your money”

I’ll echo what others have stated. If your a big HP boat, catching air all the time, DG can only do so much. After 6 failed XR’s, I gave up and got SCX’s. I just added the DG as a second layer of defense. I am a bit surprised to hear of so many failures, but I made one season and hope for many more with no issues. Good discussion nonetheless.

I had a very similar experience as waveryd. Although a very nice looking piece, it didn't help me in any way as I was breaking drives just cruising around 70mph in flat water. 3 failures in 25 hrs, but to be fair, that was with 850 hp in 28' cat with an IMCO SC, which it was never designed to handle

did you have gear or shaft failures? Who was building the drives?

First time, broke a tooth on one of the upper gears and of course trashed upper and lower gears. Second time, snapped a clutch shaft. third time, snapped a u-joint. just kept finding the next weakest link.
Boat now has a SCX on it and has been sold. As far as I know, it has been problem free for a season