actually I never used Progold. The only other lubricants I regularly used to use were Finish Line Teflon(good, but not environmentally friendly, wears of FAST), Finish Line Synthetic (not environmentally friendly, dirt sticks and makes lots of mess) and Rohloff Oil of Rohloff (biodegradable but very sticky, dirt sticks like honey).
I tried Squirt two seasons ago and it works so good that I haven't used anything else.
**It has some advantages: **
If you do it right, you'll be rewarded with a silent, CLEAN and shiny chain, without having to really clean it. (take a look at my photo, the chain is a (muddy) season old and the cassette two, no cleaning needed, apart a little bit of wiping, without any solvents, degreasers etc.)
It's very thin and penetrates the chain rollers, so it actually lubricates where it is supposed to.
It seems to lubricate very well, the chain moves with noticeably less resistance, when applied. (compared to an unlubricated chain)
If you put on too much of it (I do this all the time, because it is so thin), just spin the chain for a couple of seconds and wipe it off with a rag. It is like water and comes of easy, as long as it hasn't dried.
If it dries and you got too much of it on the chain, it is just wax. Wipe it off with a rag, it's easy and even sprinkled with dust, it comes off and doesn't make that tar-like goo.
It is said to be bio-friendly. (can only take the companies word for it, hope it is true)
It's very thin - if you don't apply it carefully, the bottle will be empty a bit faster than you'd like.
It is not cheap, get the big bottle and use something smaller to apply it.
You'll have to lubricate your chain after every long ride or after every two shorter ones. If you forget, it will start to chirp =)
You need to apply it AFTER your ride, so it can dry before your next ride. Otherwise it will dribble off.
I accidentally bought a bottle with their "cold conditions" formula. Honestly couldn't tell much difference, both worked great in winter and summer for me. As long as I applied it in my basement and let it dry there. That's also the way to go for wet weather riding (which I've had LOADS this winter). Wipe off the chain (so it is dry), apply the stuff, spin for a couple of seconds, let it dry (couple of hours). And it will work well even in rain, snow or swamp.
Okay, I am too stupid to link my pic.