Yes, the Neptune is much closer to the Hornet than the Venus is. However, UNDER NORMAL CIRCUMSTANCES, the Venus is not close to the Domination, depending on the usual many factors. Of the balls you mentioned it is the closest, due to its light particle load. (the less hand you have, the less difference between balls you will see.) The Venus can get near but not into usable on TRUE medium oil, in my opinion. It may work with a relatively strong drilling.
Having a slightly rolly core, but with a polished pearlized, light particle load, it is fairly even reacting. With the very low RG differential, you do not want a weak drill on it; I'd say nothing more 4", but I'd recommend keeping it even closer to 3.5".
Re:
"I have a Lane Masters Hornet, but as I don't have a lot of hand (300 rpms) it usually is not quite strong enough to get around the corner."[/]
300 revs is more than enough hand to get the Hornet to turn the corner. I amin that range and mine has no trouble whatsoever. More important than rev rate is the ball speed to rev rate ratio. Too high a ball speed can almost negate your rev rate with respect to a specified level/amount of oil. Of course, maybe there just was too much oil in any case.
The Venus is a proper level above the Hornet in oil handling ability, in my opinion. I have both and can see this easily.
NOTE -
Just looked at your profile. It says you have a Thunderstruck Pearl. Have you tried that, instead of buying another ball. The TP and the Venus should overlap more than a little bit, with the TP handling slightly more oil. Teh TP is also, in general, a step down from the Domination. The TP is also supposed to kind of even reacting, like the Venus, but it can go either way, as it rides the border between even arcing and skid/flip.
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"None are so blind as those who will not see."