Hi Sanna,

I have used Expand RT kit from Roche for reverse transcription of long transcripts...it works fine. The kits mentioned by you should also work properly.

One consideration for such amplifications is very good integrity of Total RNA....use kits/protocol which ensures very high quality RNA

bye

I have used SuperScript III Reverse Transcriptase for cDNA synthesis coupled with Herculase II Fusion DNA polymerase for amplification to generate a 10 kb product successfully.

But I agree with the above answer that RNA integrity is critical.  The RNA I used was isolated by Trizol method and then cleaned up using Qiagen RNA columns (with on column DNAse treatment).  The RNA was QC'd on Agilent BioAnalyzer  with RIN=9.5.

Thank you Ajay Saini and Deanna Russell. I will make sure that I start with good integrity RNA. 

FYI

Both kits worked well for amplification of a 6kb large fragment.