From my experience so far I would say pay the extra and get the SVD.
There are points for and against both some of which will come down to personal preference but here's my experiences having owned 2 Vamos and changed to the iTaste SVD in the past week.
The Vamo is cheaper and works well with the easiest to use control buttons but has one major flaw....
The 501 connection is machined from brass and wears out fast and a drop or sitting on it with the tank connected will strip the thread.
As it's a custom made 501 that has a large washer on the back it's not a simple strip and solder job, it can be done as shown in this thread:
Vamo 501 replacement
Making the part
(Any users with a mini lathe and a box of washers could find a nice little sideline making this part as there is an ever increasing pile of dead Vamos out there)
The Vamo screen is brighter and easier to see in sunlight plus is orientated horizontally which I prefer.
So despite the fact the SVD screen is (for me) the wrong way, isn't as bright and has a slightly more complex button arrangement that does lead to pressing the wrong button when trying to fire (when you first get it) I'd say it is the better product in it has far better build quality and I think much better looking and quite eye catching, it does have a few other advantages as it will take all the ego style tanks I have tried including the T3 which requires an adapter on the Vamo and seems to add to the 501 wear issue because the drip well is too narrow and won't accept the larger knurled base of the T3.
I bought the iTaste SVD kit that comes with 2 iClear 30's and think it performs excellently, I was unsure about the looks of the iClear 30 with it's knuckle jointed drip tip but was completely won over by it's performance so far and put it quite close behind my AGA-T2+.
I've only had the SVD a week so can't say anything about long term reliability but after 6 month loving the Vamo I'm very pleased with everything about the SVD now I've changed a few habits and got to know it and was pleased to see the 501 connection made out of something more solid than brass...
Hope that helps.