Hi gents,
After working with acrylic paints in the auto repair industry, I made the transition to 2- pack paints (clear over base and solid colour) through convenience.
It has been a revelation to say the least.
Initially 2 pack paint systems were very expensive here but now days decent acrylic is as (if not more) expensive as 2 pack and entails a heap more finishing work.
Most panel shops using 2 pack have been forced to go to the cheapest brands available as the insurance companies have tightened up, expecting people to work for nothing!

This has resulted in some interesting experiments with differing types of 2 pack systems, mainly using up left overs and mixing different brands.
I have had very good results with ppg clear but don't use it generally as it is quite expensive, having found that the cheaper brands such as "concept" come up very good "off the gun".
Most 2 pack systems are not fussy as to what brand/ type of hardener and reducer are used. I have even used general purpose laquer thinner in 2-pack, it goes on ok but reducer gives a bit more shine straight "off the gun".
For me to buy a litre of concept clear it costs around $85 Aud, but if I buy it in bulk I can get a 7 litre (+/- 2 US gal) "clear kit" for $155 Aud. Top brand name clear is between 50-100% more, depending apon where you get it.
The trick for me at least is to do a repair job that needs at least 2 litres of clear and then I've got free clear coats for model aircraft for ever.

I haven't tried waterslide decals under 2 pack clear yet, it won't be to far away though. I can't envisage too many problems if one doesn't use a very "aggressive" reducer.
In regards to using 2 pack clear coats, I suggest people don't be afraid to experiment on less important objects such as field boxes and the like, in most respects 2-pack is very user friendly and quite easy to obtain great results.
If using 2-pack systems, a good carbon filter is mandatory. Cover up bare skin and minimise your exposure time.

Regards, Rob.
(P.S, sorry for rambling)