It's not really about dropping money for the RJ course. It's about whether you want to take the time to improve yourself as an aviator or pay the money to skip that step.
Instruct!!!!!!!!!!!!!
Right now, with 405 hours, you barely meet the minimums (even with reduced hiring mins) for Trans States, PSA, Pinnacle, Piedmont (500 reduced to 300), and ASA (500 reduced to 400). So doing the jet transition course only makes you eligable for Piedmont and ASA above what you are already eligable for. Those are not the best regionals. You barely meet these requirements with 400 hours. If you get another 200 hours (maybe 2-3 months), you will add Comair, ExpressJet, Mesaba, Mesa, Commutair, Colgan, and Air Wisconsin. Basically you will meet just about every regional airlines minimums (except Skywest, Horizon, Republic, and Eagle) with just 200 more hours!!!! And you don't need to drop 6 thousands dollars!!
The jet transition course only makes you eligable for ASA and Piedmont. And that is BARELY eligable with no CFI time, you are unlikely to get hired at any of these airlines!! All you need is 200 more hours of CFI'ing (2-3 months), and you are then eligable for a bunch more airlines. And you will learn a lot!!
I wanted to comment on the current hiring window. You seem to be afraid that it will stop sometime soon. That is false. I want to dispell the rumor that this hiring window will stop anytime this DECADE!! Think about it. Right now all the regionals are hurting for pilots. Yet only 2 of the 6 legacy airlines are hiring! Just 2 of them. Imagine what happens when American, United, Northwest, and US Air begin to hire (in 1-2 years). American and United are the world's largest airlines, and they are not hiring. Also, none of the legacy carriers are expanding. Air Travel is expected to double in by 2020. The legacy carriers will need to expand and then hiring will be amplified! Check out this link to my pilot shortage thread. Lots of good facts.
http://forums.jetcareers.com/general-topics/45281-real-pilot-shortage.html
Trust me. Don't worry about the hiring window closing on you. It will not close anytime this decade. Only a few of the majors are hiring, and there is currently a shortage. Imagine what will happen when they ALL start hiring in 1-2 years, and then expanding. Do not let this fear play into your decision. As some famous jedi once said,
"Fear leads to the dark side." Don't let fear affect your decision!
One other thing... How much PIC time do you have? Do you know how much you need to upgrade. At most regionals, it is ICAO mins, which is 1500 hours PIC (or minimum 300 PIC and 1/2 credit for your SIC time). If you have 300 or less PIC, you need to go out and rent an airplane until you have 300 PIC, and even then you need 2400 hours of SIC time before you upgrade. That will be 3 years!! You could be delaying your upgrade because you don't have enough PIC time. That is another reason why CFI'ing is better than low time FO'ing!
Last thing. If you are worried about washing out of training, then you should definately CFI instead of doing the transition course. You learn the most when you teach it to someone else. CFI'ing will teach you the most, and be more effective in preventing you from washing out of the regionals!
Trust me, and EVERYONE else who responded to your question. Get your CFI and instruct. It will only take a few months to get where you want to go. It will also be cheaper (and you will make money from CFI'ing). You will have the PIC time necessary to upgrade (instead of staying a FO when you have seniority to upgrade to captain!:banghead: ). Also, you will still be around for this hiring window. It is not going away any time soon.
Good luck.
Let us know what you decide.