What's the wind speed range for the 1.5 SLE vented ? It says 12-25mph but thats only 5mph more than the standard 1.5 SLE ? yet it's vented and the B series vented goes upto 45mph ? I've just got a standard 1.5 SLE and want to add a vented version to my collection but not sure if it's worth it now 
In a word,
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In a few more words, by way of an explanation. I have used this analogy many times before but I make no apology for that because I believe it to be true. You wouldn’t expect to play a full round of golf with one club, so why would you expect to be able to take this Rev flying lark seriously with just one kite. Just as a golfer needs a variety of clubs for different shots, a serious Rev flyer will have a selection of kites to cope with different conditions.
Don’t pay too much attention quoted wind ranges, I think you have to look on them as an indication of what is considered possible, not what is pleasurable and let’s be honest we fly these things, for the pleasure. You have already noticed that there is a considerable overlap in the quoted ranges for the std and vented, as there is between std and the sul (Super Ultralight). The point at which kite changes are made is very much a matter of flying style and personal choice and personal choice will change as you skill and experience increase.
A vented 1.5 will be the second best Rev investment you ever make. Like you, I started with a full sail sle that was shortly followed up with a second hand vented sail (now passed on passed on to a needy student). I am now the proud owner of a full matched set of 1.5s and a super vented exp for when it gets a bit draffy. Of all my Revs, I think the vented kite has had the most airtime. All are getting a little long in the tooth now and have given me hours of pleasure and believe me, none of them owe me a penny, but the vented has been the first to require serious repair, an indication of the use it has had.
I said “second best Rev investment” because the first has to be the best, without it there could be no others.
Enjoy