If you've got piles of miles to burn and can make a reasonable award ticket work out, why not fly Biz? However, if it came down to having to purchase a ticket for cash, I'd stick to mainline carriers but fly in coach. These flights are short enough and the aircraft used not so posh...so I don't feel I'm missing much by not flying Biz. I'm not a fan of LCC's unless I've got lots of flex time in case of cancellations or delays. I'd do mainline carrier in/out of RGN as your options are relatively limited in case of IRROPs.