The geometric limit on the FOV is increased with the larger body. Typically, you cannot have a 30mm 1.25" EP that has a 67 FOV. (You can if the entry lens on the focuser side is unusually close to the bottom of the EP body, but then it might not focus properly, esp. with a Barlow).
http://members.optusnet.com.au/~jano...ep-fov-sml.png
Typical FOV geometric limits are:
1.25":
FL(mm) FOV(deg)
15 93
20 76
30 56
40 43
2":
FL(mm) FOV(deg)
15 119
20 104
30 81
40 65
... bit more with vignetting