Just flew VX last night SEA->SFO. The WiFi (accessed on my Android phone) was fine, and gave a measured 1Mbps down/375kbps up using the SpeedTest app.
Would definitely NOT suggest a tall passenger fly in economy transcon with the small seat pitch if a larger pitch is available, even on another airline. The E+ exit rows and front row on VX are not bad at all though, and often don't cost much more (and have minor bonuses such as free checked bag and free food and drink).