Good write up which I agree wholeheartedly with.
I'd add he's also very good in the air, which, added to all you note; makes him a far better all round footballer then the current young crop who all have differing facets to offer but not the rounded game Saido does. The quality and variety go his goals really impressed me last year as much as his all round play. A poacher like Kane you can see struggling when the rest of the team struggles but Berahino offers you a whole lot more from a variety of different situations. And as to the perceived 'attitude problem' .... he's ridded himself of that by having the nounce to boot his dip**** agent to the curb. (Something other young prospects could well heed and follow.).
As regards Utd, with money being no object as we keep hearing; I wouldn't think twice about making that investment for the future.
Still young enough and willing to learn to mould him how you want him whilst being able to contribute something different on the park through that continued development.
Kane is also decidedly better in the air than him.
I doubt he leaves West Brom, at least this window; but he'd be a great calculated gamble IMHO for any of the top 5 clubs.