Best advice I can give you is don' let the Ovangkol haters cloud your own personal judgement of what sounds good.
Warwicks are one of those basses that are really hit or miss, especially when they went the ultra mass-production route. The ones that were a miss were really a miss, but the ones that were good were amazing. To this day, the best sounding Warwick I've ever heard was an all Ovangkol Thumb BO 5 that was hanging on the wall at a local GC right around the '00 or '01 time period. Keep in mind, by this point, I had probably owned a dozen or so Warwicks over an 8 year period, almost all of them with Wenge necks, so I had plenty of expertise in this matter.
Now, to your question, a Wenge neck and board is going to have an upper mid presence that is pretty hard to replicate with other woods. Some like this mid bumb while others hate it. If you're more of a traditional "Fender Jazz" fan, then you're probably not going to be wild about the Wenge/Wenge combo tonally, especially when matched with a Bubinga body which has a similar mid characteristic to go along with it.
Ovankol is an interesting wood. Ovangkol (also known as Shedua) has a density that is very similar to Bubinga. In fact, I believe the two wood species are from the same family. So Ovangkol and Bubinga sound really close whcih is why I think Warwick choosing Ovangkol for the Thumb BO was brilliant as it kept the price down yet gave the tone that many wanted from the Bubinga.
As a neck wood, Ovangkol is extremely stable, and again, pretty dense, not quite like Wenge, but very close. Tonally, I'd say that the Ovangkol has more of a lower-middle mid rather than an upper mid presence that Wenge has. I personally think the feel of Ovangkol is very nice, and you never have to worry about splintering like you do with the Wenge.
The addition of a Ebony board with an Ovangkol neck is pretty nice too. It's certainly getting you further away from the classic Wenge/Wenge tone, but it gives you a little more in the lows and possibly sweeter highs as compared to the brittle/harsher treble response of the Wenge.
Bottom line is that you should play a bunch of Thumbs, and pick the one that sounds best to you, regardless of wood combination. One thing to keep in mind is that the electronics in Warwicks are easily their weakest link, and they're also the easiest to modify down the road if you decide that the tone isn't working for you.