Mardy, You'll have a lot of fun with your new Jab, but you will have to do tappet adjustments at regular intervals. As I understand it Jabiru went to hydrolic lifters to prevent having tappet adjuster failures caused by ham fisted owner/operators. I've owned both types and I used to think that although a relatively simple task, adjusting the tappets was a pain in the you know what. I don't believe there is sufficient evidence to suggest hydrolic lifters are a backward step, only speculation in some quarters. Initially they did have to change the profile of the camshaft and I think they had a couple of versions before being satisfied. The key to safe operation is to be vigilent with maintenance (use an L2/LAME where necessary)and get the cowls off often for a good visual inspection for anything that may need attention. Do leakdown tests every 100 hrs and keep a close eye on the oil level as it will use 50ml/Hr or more - don't overfill as it will expel excess oil out the breather. It's a good idea to do a pull through before each start of the engine and get a feel for what's normal and you'll be able to pick any problems before they arise. Common sense really.!!
Cheers and happy flying,
Billwodmason.