There is a possibility of some cash coming available for me to use towards cycling, I will have about a grand to spend. I have been thinking for a long time about getting a MTB and have one picked out that I like. The thing is that I haven't been MTB'ing in years and not at all since my accident. I don't know how I will handle trails without being able to clip in and out easily on the one side. My other option is to use the money towards some goodies for my road bike.

I have been eyeballing a nice set of carbon bars (Zipps) and stem along with a lighter seat post for some time. I had also given consideration to a better set of wheels. I am not unhappy with the Aksiums that I have now, but can't say that I would mind dropping a bit of weight. I would use my current wheels, as well as my seatpost on my son's bike if I go that route. Otherwise, I am very happy with my road bike as it is. Any future upgrade to the group or the like would only be in the case of crash damage, or to upgrade the group on my son's bike.

Ah, I love having to make decisions like this...

A grand will not get you a fun dual suspension MTB, but it might get you a decent hardtail. I vote to upgrade components on your road bike, which you seem to be enjoying more as of lately.

upgrade the Felt. I know what you mean about the Aksiums, got rid of my set and got a set of Ksyrium Elites on closeout and have really enjoyed them. I also got a deal on a Felt VS carbon bar and it helps out with the road buzz in my hands.

Really? Is this a question? Upgrades are a waste of money unless you have specific parts that really aren’t functional. You Will probably have to try really hard to notice the benefits of replacement handle bars or wheels, but a mountain bike opens up a whole new world of additional riding fun.

I have been looking at a Specialized Carve Comp that's on sale. It is more bike than I would ever need, and wouldn't need a thing aside from possibly a seat for what I plan on using it for. It already has hydraulic disks, 29'er, and a fork lockout as well. Honestly, my rear fear about going mountain biking is the fact that if I lose balance and go off the right side I am going to eat it. A problem that I really don't have riding on the road since it has such regular surfaces.
I have this beautiful set of trails five miles from my house, and it feels like such a waste not utilizing them...years ago the only thing around to MTB on were renegade spots.

You have a prosthetic that needs to be clipped in, right? You could still be okay on the MTB as long as you know your limits, but that's true of everybody on the trails I think.

Go with a set of Speedplay frogs and you will have no problem clipping out.

I am currently using Crank Bros Eggbeaters. They work really well for me, and being "always up" is very helpful. The issue is that I have almost no rotation in my prosthesis side, so I cannot unclip without either having my good foot on the ground, or having to make a really pronounced movement on that side to achieve the rotation.

Get a hardtail MTB if you want to explore trails. It will open a new world of riding. Nothing says you have to be clipped in, you could use a plain old platform pedal. Or you could use toe clips, leave slightly loose and you can pull straight back to get out.