Since you have the Red 3 won't the API 2500 be redundant (or SSL comp for that matter) as you already have 2 buss glue compression covered? I'm of the camp of many different comps and a patchbay instead of the one expensive comp trying to cover a lot of ground. So break down the ground you want to cover. There will be some inexpensive options for part of that list so don't rule something out based on price. Obviously a FET (1176) fast attack type comp will be on most guy's list. For clean / transparent the Aphex 651 ($150 used, add another $150 for Jim Williams to mod it if you need it super clean) will cover that ground for not much money. For the DBX signature VCA sound I'm partial to the DBX 160X, $150 used. You get the idea, figure what ground you need to cover and we can help narrow it a bit further.