I have spoken to guys who have flown with the van horn blades and they say they are a noticeable improvement. To be fair that would not be hard to achieve. Poor old longy is a bit short in that department above 10000 and by 12000 I would say it is your limit.
If you can afford it got the 407 blades. I believe they are unboosted on the Longranger but they have amazing authority on the 407 so would be even better with less gross weight. I cannot imagine the 407 blades running out of puff.
The 407 book, from memory says the 407 can handle a 35kt wind from any direction in the hover at 14000 feet. Can't imagine the van horn even getting close to that. Not sure what is involved with the 407 upgrade. May need new gearbox, driveshaft, boom etc.