I've a Cyclone carbine and Typhoon, both .177 - Cyclone has L/W barrel & Typhoon the ST barrel, both will stack pellets at 30 yards, I've had no real problems with either.
Wife has a Vermy MK1 .177 with a ST barrel, only problem with that is the brass insert for the grub screw that holds the stock to the bottle will 'pull' if tightened too much.
Youngest son has an old Typhoon with a L/W barrel, again no problems with it.
I've shot a Bobcat & Impact, nice guns, just not for me though - mind you, will probably 'go' for a Wildcat when I get the chance/money together.
ASI (the importers) are great (so long as you don't try to take the p*ss), very knowledgeable about the guns, and will take the time to sort any issues out.