In my experience with the Lab Ray, it's been either extremely horrible to me (current lab rat: SolarStar226, Disco Nimmo) or beautiful and wonderful to me (old lab rat: Brezenae, Island Ruki).
I've had numerous species changes (Grundo to Techo, Kacheek, Bruce, Uni; now currently Nimmo; & Green Ruki to Red, Yellow, Shadow, Cloud and finally Island), colour changes (White, Island x 2, Fire, Cloud, Yellow, Christmas, Disco), stat raises (more raises then drops) but the Level has suffered immensely. So if you're going to have a high-level pet by the end of it, if you're a battler, stock up on codestones & dubloons.
My tip would be for you to have at least some kind of backup for your pets, just in case the Lab Ray doesn't want to give you the desired colour for the pets you have - I would suggest saving up for transmog. potions for your Kougra & Jetsam as a precaution, and for the Bori (considering the only potion on trades is 500k minimum), well, I can only say good luck and I hope the Lab Ray is kind to you ^^;
But Level drops aside, the Lab Ray is a good investment. I got mine early weeks of 2003/2004 and it's served me quite well, as those owners who have my old pets, Ten_Cents17 & babatasha, can agree.
Keep saving, set an NP goal every day. You'll get there
