i am looking for some opinions before i purchase a kayak (most likely a mirage oasis).
Sundancer, welcome to the forum. We're on our 3rd generation Oasis and absolutely love it.
we rented a kayak saturday and was out for a little over 2 hours. while great fun, the rented kayak made my good leg fall asleep and the provided back support - didn't support.
Hopefully it wasn't a Mirage Drive!
now i know this is mostly due to the 'rented' issue. the hobie costs a substantial chunk of money and i wouldn't want to experience the same with it.
Many dealers have demonstration boats. Before making any final decision, you should take a demo and make sure your leg is comfortable propelling your boat.
will i be buying replacement seats right away?
Most owners like their seats, although everybody's back is different. Personally I have replaced the stock seat bottom with the optional "i-comfort" Hobie option -- huge improvement IMO.
what are 'right out of the box' upgrades?
You should get a cart. I'm a big fan of the standard cart for the Oasis unless you're going across soft sand. In that case, the Trex cart would be the preferred cart.
I'd start out with at least one set of "ST" fins. They're just about as easy to push as the standard fins and more efficient. If/when you find your leg handling this well, you will probably want to get the ST Turbo fin upgrade for your Drive. The standard fins are very rugged though and can be a preferred choice for use over oyster beds and other such abusive underwater objects.
what are you experiences with the mirage drive? (is it prone to getting fouled with grasses, etc)
The current Mirage Drives are great -- easy to install and remove (after you learn the technique), durable and relatively easy to maintain. The fins do collect sea grass though. You can either pop the Drive up and down to release it (takes about 15 seconds) or ignore it and let it slough off naturally.
Some folks mistakenly believe the Mirage Drives are limited in shallow water to hull displacement plus length of the fins. In fact, the fins can operate using a flutter kick in very shallow water, as this composite pic shows:
what are your experiences with it generally?
I've been using the Mirage Drive system for over 10 years and have not found anything else like it -- have tried a variety of paddling and pedaling kayaks. The biggest advantages IMO are 1) hands free operation, 2) speed and range, 3) superior performance against wind and chop, and 4) versatility (they make fun little sail boats as well). Additionally, Hobie has an excellent reputation of standing behind their products.