Dictionary compression effect can be easily tested with any sequential compression algorithm, via diff(compress(dict),compress(dict+file)).
Code:
100,000,000 enwik8
465,211 dict1 // DRT dictionary
133,741 dict.7z // 7z a -m0=lzma dict dict1
25,895,917 file.7z // 7z a -m0=lzma file enwik8
26,015,709 dict+file.7z // 7z a -m0 dict+file dict1 enwik8
25,919,495 file.patch // hdiffz.exe dict.7z dict+file.7z file.patch
// 25,919,495>25,895,917 - bad dictionary
100,000,000 enwik8
768,771 dict1 // BOOK1
261,068 dict.7z
25,895,917 file.7z
26,140,756 dict+file.7z
25,879,830 file.patch
// 25,879,830<25,895,917 - better?