Yeah the idea is that students can feel comfortable in any fighting range. If a wing chunner tries to close the gap with every opponent, he/she will find themselves one day strugglig, especially against someone who is good on their feet (karate guys, boxers etc). The idea is to be able to 'hold your own' until an opportunity presents itself
We don't want to train pro boxers, but give students confidence in every area, rather than leaving them trying to tan sao a roundhouse kick!!
I have started training intensley in other arts and it has really boosted my confidence. I am pleased to say that the wing chun is extremely effective against the other artists (even black belts). About 1 in 9 times I would get caught by a quick high kick or fast back punch, but generally the reactions of wing chun and strong structures came in handy
If anyone doubts their wing chun, my advice is to go out and try other arts. Most arts like boxing, karate, BJJ and TKD are extremely quick but you will see straight away how your skills fair
(and that was not meant as a reccomendation to go and challenge other schools or 'try it on' with their students, but go in humble and you will see where your wing chun works)
I don't understand how you can spar with another style and then compare them equally. For wing chun to be effective, you have to go at 100%. This is when you're utilizing it at its true speed. Sparing or love tapping doesn't work with us because if it were a street fight a single move could have more then one objective. It's either on or its not because we're a striking art. You stated something about tan sao'ing a roundhouse kick. Why would you do that when you can merely step in and close the gap. A good fighter CAN use a kick to get out of a close range situation but most fighters can't and wouldn't waste the energy or time to do so because there are easier options at that closer range.
I do agree, you should play around with people of other styles or arts. So that you may learn a more diverse range of opponents. I wouldn't call it sparring though because you are playing by their rules.