I'm not sure 333 will have smaller or less fruit but like everyone I've heard the rumors. There are people that say they are less vigorous. I'm looking at some of the new rootstocks here http://treefruit.wsu.edu/wp-content/uploads/2014/12/pear-trees-rootstock-txt.png and see this link http://treefruit.wsu.edu/varieties-breeding/rootstocks/
Yes I normally would not gamble with 100 rootstocks right away like I did with 333 but I needed to get some in the ground. I normally do test crops with most fruit. The new pyro dwarfs are reportedly good but I know even less about them. This is what is said "PyroDwarf produces a tree 61% – 70% of the size of a seedling pear tree. It is an alternative to seedling rootstocks, as it produces large attractive trees which start bearing usually after 3-4 years. Being of Pyrus origin, there are no graft incompatibility issues with this rootstock. PyroDwarf is able to tolerate chalk / alkaline soils better than quince-derived rootstocks. PyroDwarf was developed from a cross between ‘Old Home’ (fireblight resistance) and ‘Louise Bonne dAvranches’ (ability to strike hardwood cuttings) pear varieties made by Helmut Jacob, at the Research Institute and College, Geisenheim, Germany, but has only inherited some of the ‘Old Homes’ fireblight resistance. However, it has been reported that this variety produces severe suckering with spiny shoots, as well as causing reduced fruit number (T. Auvil, WTFRC). Source: orangepippinstrees.com" - http://treefruit.wsu.edu/varieties-breeding/rootstocks/
I'm looking hard at the pyro dwarfs now for future plantings of pears due to my alkaline soil. This is what is said of 333 that I'm basing my concerns from "A semi-dwarfing pear rootstock. It is 1/2 to 2/3 standard size. Its resistance to fireblight, collar rot, woolly pear aphids and pear decline make this a very healthy stock. it is not very precocious and gives few fruit and with reduced size (T. Auvil, WTFRC). Source: Cummins Nursery" - http://treefruit.wsu.edu/varieties-breeding/rootstocks/
That initial report of 333 sounded pretty negative but this report is not as bad which came from the same source http://www.cumminsnursery.com/pearroot.htm
The OHxF series of rootstocks originated from crosses made more than 75 years ago by Reimer at Oregon State. Reimer was seeking primarily rootstocks resistant to fire blight; both the Old Home and Farmingdale parents are highly resistant. Reimer's work was continued by nurseryman Lyle Brooks and by researchers at Oregon State. All the OHxFs are propagated by cuttings or in tissue culture -- with considerable difficulty, as all are reluctant rooters.
OHxF333 A semi-dwarfing pear rootstock. It is 1/2 to 2/3 standard size. Its resistance to fireblight, collar rot, woolly pear aphids and pear decline make this a very healthy stock. Precocious, well-anchored. Trees are very productive. Some reports that fruit size is reduced
OHxF 40® A semi-vigorous pear rootstock, about 2/3 standard size. Resistant to fire blight, crown rot, woolly pear aphids, and pear decline. Precocious, well-anchored. Patented; royalty 50¢
OHxF 87® A semi-vigorous pear rootstock, about 2/3 standard size. Resistant to fire blight, crown rot, woolly pear aphids, and pear decline. Precocious, well-anchored. Patented; royalty 50¢.
OHxF 97 A vigorous pear rootstock. Standard size, but more precocious and productive than seedling stocks. Appears to be especially valuable for Asian pears.
DWARFING PEAR ROOTSTOCKS For many years, pears have been grafted onto quince rootstocks to obtain dwarf trees analagous to apple trees dwarfed on Malling 9. Most varieties of pears are more or less incompatible on most quince clones (but in several instances, including Bartlett on Quince A, expression of incompatibility may often be delayed until 8 or 10 years or more in the orchard). All the quince stocks we have tested have been quite susceptible to fire blight and most are somewhat winter-tender. Even so, there are many outstanding plantings of dwarf pears in commercial production.
At Cummins Nursery, we graft onto Quince only those few varieties known to be compatible.
SEEDLING The industry standard. Pear seedlings are still quite satisfactory if proper care is given. Pyrus betulifolia ("BET") seedlings are the rootstocks of choice for Asian pears. A number of extensive field trials have shown that fruit size is increased significantly as compared to other rootstocks. We also use Winter Nelis seedlings -- somewhat more winter-hardy than BET. "