I swopped my 15" woodrim for a 14" leather as the woodrim was giving me cramp in my hands.
Richard, I looked into this when I first got my car. Others I'm sure can correct me if I'm wrong, but a "dished" steering wheel such as yours pushes the wheel a bit closer to your chest (the wheel spokes are therefore kind of cone shaped), allowing for more room underneath it for your thighs. To me this is not a good solution as the standard wheel feels pretty close to my chest as it is. Moving from a dished to a non-dish wheel of the same diameter will consequently give you less room.
An "off-center" wheel is not round, but rather is a bit rounded off/squished upward/"shorter" (closer to the hub) at the bottom when the front wheels are pointed straight ahead, thus giving you a little more room to slide your legs underneath, making ingress/egress a little bit easier. It does kind of "wobble" a bit when you turn the wheel, though.
The advantage of a larger wheel (leaving aside site lines to the instruments) is that it gives you more leverage, thereby reducing the steering effort needed. If I were you I would consider moving to a smaller, thick-rimmed wheel, 14 or even 13. You can check these out on the Motolita web site. If you find steering difficult as a result, you could consider installing a power steering system (such as made by EZ), but then you're starting to talk a lot of money. Note that steering effort is mostly an issue while the car is completely stationary -- once you're rolling even just a little bit the steering lightens up considerably.
