Urea vs urea free fertilizers

[avian]

I've been using Grow More 20-20-20 and my orchids seem to be OK with that. Only use @1/4 tsp in a gallon per watering most of them time. Every few weeks I just use plain water. I was wondering, though, if it would be better to use urea free fertilizer such as Grow More 20-10-20 or something else.
20-20-20 strength was recommended to me by a very reputable orchid grower/hybridizer. Never specified a brand or that it should be urea free.

[Ray]

Orchids can use all three forms of nitrogen - nitrate, ammoniacal, and urea - but urea is the least-well absorbed of the three.

1/4 tsp/gal every 5 to 7 days of either formula is fine.

[rbarata]

If I'm not mistaken, urea fertilizers require a regular plain water watering to prevent salt accumulation in the medium.