As long as all you're asking for is opinions and not facts, here goes...
Its real tempting to put a 50mm objective scope on a 22. I did it once. The more light the better, right? But after a while it just looks odd, like that little alien on the Bugs Bunny cartoons. I think a 32mm or 40mm objective is proportional to the size of a Speedmaster and will not detract from its walkin-around-iness.
I would get the appropriate parallax for a 22; 50-60 yards or Adjustable Objective. 22LR and smaller are not 100 yard guns. The sound wave out of a std velocity rimfire cartridge catches the bullet at about 60 yards and messes with it, so a long accurate shot with a 22 hunting round ain't happening.
I like Leupolds.
Have a FX-1 4x28 on a 10/22; proportionally-sized for the gun, 60 yard parallax, fine duplex recticle. I can shoot 50 yd groups better than I can see. And if its 100 yards away, thats where the semi-auto part comes in; keep shooting at it until you hit it, for 3-5 cents a shot.
Have the VX-II 3-9x40 AO on a CZ 452 bolt 22. Very accurate set-up. The AO has yardages on it; for 100 yards and under, its not real critical to get it set exactly, but it is more accurate if you do.
DrDoug's Weaver 3-9 AO sounds interesting.
If you want a 4-12x40, look at the Bushnell Banner 4-12x40 AO. Its a little bulkier than a 3-9 but I think a heavier 22 like Speedmaster can handle it . Had one on an NEF 223, then on the CZ 22, no complaints. ~ $120 at Opticsplanet.com
Someday, a Speedmaster is coming home with me.