I mean loss of money on the 45lb wing now that I need a 30lb.
Why not see if you can exchange it? If it's still unused, they may agree to an exchange.... it'd demonstrate good customer service if they did.
If not, and it was unused, then you could always try listing it on Ebay/Craig's List, at the full value... or for a swap. You might get lucky and find someone that needs a doubles wing, who has a single tank wing spare...
If not, then I'd advise on making do with the 45lb wing for now, so that it doesn't force compromises with your other equipment needs. When you eventually get a dedicated single-tank wing.... you'll be pre-equipped for the transition to double tanks at a later date..
But I just checked out the oms site and they market the 45lb as a ideal single wing when used with an sta. This is getting confusing.
Rule #1 : Never believe the marketing.
Combo single/double tank wings, Spare Air and Split Fins are the most misappropriately marketed scuba items. But there's plenty of other misleading advertising done, even on good products.
Would a console computer be ideal since I will need an SPG anyway?
My standard answer to this is: "Where do you wear your watch, and why?"
If you find it more convenient to have your watch dangling at your waist on the end of a piece of string, then it probably makes sense to get a console... If not....
If you search this forum, you'll find lots of (heated) debates about console/wrist computers and single/double tank wings... it's worth considering all the perspectives.