Hi stringy and thanks for the flattering comments! I seem to spend more time visiting grandchildren in Arizona these days. There is water there but most of it ends up in farmers' fields. I have a kayak there and am hoping to get some quality boating during the spring planting season when the fields are flooded! There is a local dealer in the nearby town of Tempe but I don't get the opportunity to spend time his newest gear extensively like I can here -- he probably doesn't like having cabbage leaves in his equipment!
Nevertheless, I'm happy to share my impressions so far.
I have tried the new GT Drive and think its great. I have a couple and use them almost exclusively. IMO the reliability is as good as the plain bearing model but with less pedaling effort, and more forgiving maintenance and adjustment tolerances. It's best advantage comes through in longer distances where its lower friction reduces fatigue.
Assembly and disassembly requires a little more patience since the bearings have to be placed individually. This is greatly aided by making temporary plugs (or saving the ones that come with the kit) the same diameter as the shafts. They hold the roller bearings in place during assembly and are pushed through when the proper shafts are installed. I like to use pictures for illustration in such situations, but unfortunately haven't gotten around to doing this yet.
I don't see any downside to the new GT Drives in terms of durability.
The bearings are packed quite snugly around the shafts. For my own use I have removed one bearing from each of the shafts to allow more rotational freedom for the bearings. In actual practice I can't tell the difference in performance and am not recommending that users disassemble their drives to do this.
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I have also spent some time with the new Vantage seat, but only in the Revolution 11. Since the seat fits differently in each model, it's inappropriate to infer certain qualities with respect to the other kayaks. Nevertheless, these seats are all the fashion at the moment and Hobie has done an excellent job in overcoming some of the inherent limitations.
I see three solid advantages in the seat:
1. For all those who can't stand a wet butt, this is a Godsend!
2. The back mesh fabric breathes, eliminating sweaty backs and adding to overall comfort
3. The seat removes easily and makes a great camp chair -- comfortable, lightweight and versatile.
Seating comfort differs greatly for most of us. IMO this seat is more comfortable than its predecessor. I still use an i-comfort pad on the seat bottom -- it works great for pedaling over time by reducing pressure on the tailbone. Others find the seat very comfortable all by itself.
Adjustability is excellent -- you can angle the back, the bottom and adjust the lumbar. For the Revo 11 I keep the seat in its lowest rear position for stability reasons. Also with the Revo 11 it adds 1 to 1.5 inches of cockpit space for the legs, extending the versatility of the boat itself. This may or may not carry forth to the other models, depending on seat placement.
The seat has a hidden mid-back adjustment. If you find it a little flat across the mid back, you can loosen the two barrel screws (one on each back side-rail) to relax the fabric. This is not a Hobie-recommended adjustment, but I find it improves the seatback comfort and increases support near the shoulders. For those who decide to try it, you should 1) be careful not to unscrew the fittings too far, and 2) use some Locktite Blue to stabilize the new position. Perhaps one day Hobie will put a pair of knurled knobs there for easy adjustment.
The biggest disadvantage with the seat IMO is with sailing. It limits hiking out -- with the Revo 11, this is a big limitation. This may not be an issue with some of less tender models or with use of the Sidekick.
On the other hand, fishermen and those who sit in the boat for extended time should especially like this seat. My only advice is to keep the seat low for best stability. If you want to run with it raised, do a few hard turns and get a good feel for your limitations. This may not be any concern with wider boats -- Outback, Oasis and Outfitter, but I haven't tried these applications. It's always advisable to demo the products first whenever possible!
Again I apologize for not having more comprehensive impressions, but have enjoyed reading some other valuable reviews and comments by other forum members on the new products!
P.S. The new scupper drain is totally cool. You can lock it open, leave it closed or operate it with the pull of a string. It needs at least about 3.5 MPH of hull speed to drain water from the seat area -- 3.7+MPH gives good positive venturi draining.