If the Mark II is the KMK678 "Slabside" , then,
1.) My Mark II is a bit better accuracy wise with open sights than my 22/45, mostly because the longer barrel is a bit more stable. At ranges under 25 yards, there is little difference between the 2 of them.
2.) Not sure, but if a good fast pointing and reliable .22 will work, the 22/45 fits the bill. The grip angle is a bit too straight to make pointablility as easy as say a High Standard, or even the Mark II, but the high front post sight is easy to pick up and more than makes up for the straight grip. I shoot a lot of 1911 and Hi Power, so I tend to favor a straight grip. YMMV, depending on what you're used to.
3.) I would have to rate my 22/45 above my Mark II in reliability with any and all ammo. My Mark II will balk at certain hollow point loads, and refuses to feed Winchester X-pert's. Seems like some of the shorter rounds and a few of the hollow point brands like to dig nose first into the little feed ramp. Takedown of the 22/45 seems faster and the trigger is a bit smoother than the Mark II, due I believe to the polymer frame of the 22/45. The polymer is just slipprier(sp) than the steel. Speaking of slippery, the polymer frame of the 22/45 can get slippery if your hands are wet or sweaty. Some of the people use skateboard tape to maintain a good non-slip surface.
4.) No. Sorry, my 22/45 is box stock. It shot like a house afire right out of the box, and I left it that way. I've seen a full race Volquartsen in a Mark II and handled it, but didn't get a chance to fire it. The trigger was pretty good, and it cycled veeeeery smooth. Honestly though, for the money, you can't make a Ruger into a $mith 41. There is only so far you can go with the action.
When you say a reasonable price, based on what I paid new for my 22/45 20 months ago, which was $205.00, I would think long and hard at anything between $200-215, really bite my nails at $175-$200, and anything less would be a no brainer. New ones in blue in my area are going for $240.00 to $260.00, depending on the dealer. Some of the shows have them for $210.00. I looked at a replacement for mine, not that mine is worn out, I just wanted to retire it out of the rotation when it hit the 30K round mark. FWIW, I got what I considered to be a decent deal on a Browning Buckmark Camper for $200.00. I like the Buckmark a lot. More than the 22/45, but in a different way. If I had to choose between the 2 though, it would be the 22/45 any day of the week. It shoots like it should be twice the price, and it seems just about as indestructable as a Briggs and Stratton 3.5HP engine.( I ran one of those for 5 years with no oil---ooops!)
[This message has been edited by RAE (edited June 23, 2000).]