Yea, LN Engineering is great. They make excellent CNC billet alloy cylinders for the 356 and early 912 engines.
You raise a valid point, and I agree. You properly pointed out that as far as the Head/Block interface is concerned, the proper head gasket will most likely eliminate any concerns. Perhaps they're using the Steel liners in order to stiffen the engine as they mention an issue with the engine twisting, maybe this is the fix.
As far as a warranty, AutoFarm gives a 12 month/12k mi. warranty which is pretty standard I think, not better, but standard.
I checked their site and they mention that the liners are produced by Perfect Bore LTD. of Andover. Perfect Bore LTD. is now part of the German owned Capricorn Group. These guys are well respected and have been making engine liners for Formula 1 applications since '95 and have been doing Nikasil coating since '99, so they seem like a good outfit -
http://www.capricorngroup.net/en/standorte/andover-gb.html
The early Lotus engines used cast iron liner, Ferrari used them too. The Brits have a history of using cast iron liners in alloy blocks.
I admit, an alloy liner is probably better, and I'd rather have it. But I doubt the steel ones present much of an issue if you get the head gasket right.
It's interesting that LNE is producing them. That would seem to indicate that there are people out there who are rebuilding or modifying these engines beyond the current DME Flashing/Exhaust/Intake methods. That traditional engine building techniques modifying the internals such as Bore/Stroke, Cams, Cranks etc. may soon become more widely available. Glad to see that! :dance: