Basic reply from someone similarly qualified and experienced as you, though a hirer rather than owner of decently equipped aircraft.
I would go for an IR like a shot if I had the money. Access to Class A being desirable for the type of flying I would like the authorisation to undertake.
I also have the feeling, though stand to be corrected, that that access to class A essentially confers some additional safety, particularly in the UK, where standard routings could be used rather than trying potentially in IMC to find places to squeeze between Class A and MSA.