I’ve no idea on the ‘improvement’ that Pro 4 brings but I may have a pair of wheels that you might be interested in. Firstly sorry for the shameless plug.
I have the wheels that came with my Whyte 909 that are totally unused, Hope Pro 2 rear hub with 40 tooth engagement and WTB Asym I23 rims, with Tubeless strips fitted and valves supplied, the front hub is a Whyte branded generic sealed bearing job with 15mm thru.
The full spec is on the below link and I removed the tyres, discs and cassette when I got it so the wheels have never been used. I’m looking for £200.00 posted – let me know if you’d like any pics adam.buckland@hotmail.co.uk
http://whyte.bike/gb/909-2/
Cheers