It really depends on what you want to do. Do you plan and direct a bridging exercise or do you want to do hands on work and make the officers plan happen?
Lots of NCM`s either have degrees, masters or are working on them in some capacity so to go Officer solely because you have a degree is foolish IMO.
Based on my experience of Signals Officers at my unit, fresh new OCdt's seem to progress slowly (I'm not sure if this is their availability, lack of courses or just bad luck) and they don't seem to get to participate as much as untrained privates do (Your mileage may vary). I'm not sure, but it would be something to look into. The courses are also longer so that may likely have something to do with it. However it does take quite sometime for an engineer NCM to become qualified, but based on what my friends from basic said once they have SQ/BMQ L they could do OJT.
Personally for the most part I enjoy be an NCM, it has allowed me to test the waters and boost my confidence tremendously. I'm also at the point now where I am in charge of a tac rad detachment (2-3 guys), and have to ensure we have enough fuel, food, water and try to balance the sleep as much as possible between the troops.
" As well, if I decide to transition to the regular force, how difficult is it to complete the merger, especially if you are changing occupations? The reserve choices I had are infantry and combat engineer. Both choices are extremely enticing, however if I did decide a full-time career in the forces is the right path for me I would love to try and get into firefighting."
Here is massive thread of Component Transfer's. http://army.ca/forums/threads/12797.0.html
In theory, it is a one page form with some information about you and your unit, it is not a hard a process however currently they are understaffed so communication is very minimal. There are spots allocated based on entry plans and you can see the entire intake plan it is called the SIP (Strategic Intake Plan). There are various entries plans for NCM trades such as NCM-SEP, CT(U) (Component Transfer untrained) , CT (T) (Component transfer trained) , External Etc. It isn't harder to submit a ct from Inf -> Inf CT (T) than Inf -> fire fighter CT (u), however there are typically more spots for CT (T) rather than CT (U).
Hopefully some other reserve NCM/Officers can chime and give their 5 cents.
Personally I like being an NCM as I get to to "do the job", however I have a CT in myself and I am constantly contemplating between NCM/Officer.
I have seen people in my unit go from MCPL -> 2Lt, Sgt - 2 Lt etc. It definitely can happen. If you want to start as an NCM and then eventually become an officer it is a possibility, however there will need both spots available and you will need to the support of your COC and proven that you can handle the job.
Personally I'd recommend trying it as an NCM and see if you like it, however that is just my opinion.
I'm not sure about the Res officer - > reg firefighter.
Good luck