The C-27J is a fine aircraft, as is the C-295, but let's not try to squeeze ten pounds of requirement into a five pound aircraft. Both are 'intra-theater airlifters', meaning they have limited range and payload - meaning they are not practical for the deployment of heavy equipment, lots of cargo or very many troops much beyond Europe, i.e., for supporting battlegroup training exercises in Sweden, Finland, etc. They ARE ideally suited to support a deployed force in theater - think Liberia or Afghanistan - delivering cargo, equipment and people to/from the theater airhead - Kabul - amongst outlying operational locations - Herat, Kandahar, Mazar-i-Sharif.
This is not a criticism of these a/c or their potential contribution to Defence Force deployments and humanitarian crises. But if this is what the IAC gets, that means other airlift means are required to operate to/from Ireland and the theater. Of course, this is required in any case, even if a much more capable C-130J-30 is obtained. That's where collective capability partnerships come in, such as the European Airlift Group, which will match the pooled capabilities of members against the overall requirement - such as force deployment and sustainment or a humanitarian airlift.
The important factors underlying the need for an airlifter are:
1. Ireland should participate in the collective airlift effort in return for obtaining airlift assistance when required
2. That said there remain circumstances when Ireland requires a national airlift capability, such RW training and crisis response RW deployments - hostage rescue in Africa, etc. - remember when British troops were taken in Sierra Leone a few years ago. Also for the ability to evacuate (mass) casualties among a deployed force from potentially remote locations - think of PRT's in Afghanistan or peacekeeping in Darfur or the Congo.
PS. The C-295 actually carries a larger/heavier load than the C-27J, though the C-27 cabin interior is higher. The C-295 also has greater range than the C-27J and costs less. While two 295's or C-27's could be purchased for the price of a single 130J, but my vote still is for a 130J-30 because of the Herc's significantly greater capabilities. The drawbacks of having a single, more capable airlifter versus two less capable ones are outweighed by the benefits of endowed by the greater capability.
I do ramble on.....