the key mark of lightjet prints if you ask me is its size! I've never known of pro shops doing lightjet prints for anything less than 15R cos its not cost effective. A lightjet machine is also flexible in format. Its good for panaromic enlargements if you ask me because you are charged by per square inch.
As to the issue of inkjet vs lightjet/dyesub, i dunno whats the latest technology around but i recently received a free complementary A1 print from epson and kodak printed by the companies themselves. The kodak/durst epsilon looked a lot sharper and nicer (subjective) and more accurate, than the epson 7600.