Jacko,
The external stowage option may well be looked at again, but I believe that the AAC have tried out the cabin volume demonstrator and declared that they are happy with it.
As to the missing data fusion and other systems integration capability, I'm not sure that it will be an immediate limitation. It will take time for crews to get up to speed with just what FLynx has to offer and it may well prove to be better to shape the required level of systems integration after initial front line experience.
FLynx has very little in common with the Thai/Malaysian/Omani SL300. It has a completely different cockpit and mission system, much better sensors and DAS fit, and a significant improvement in radar fit for the SCMR variant.
I can't tell you on a public forum the exact details of legacy kit that's being re-used, as I'm sure you will appreciate. Suffice to say that it won't pose a problem for the AAC guys and girls and will only (hopefully) be a minor issue for the FAA.
VP