You might want to ask someone who's actually done it (and preferrably recently) before you make a decision such as that. While the Q-Course for 18A candidates is still somewhat more of a gentleman's experience than the enlisted version it's still no joke. And presuming you make it through you'll be handed an ODA with 12 very experienced soldiers who will challenge you unbelievably more than what most other officers experience during their entire career.
Ultimately though, only you can know if it's the right choice for you. Here's some questions to start off with.
First of all, are you unbelievably driven to do this or do you just think it'd be "cool?" If this isn't what occupies your thoughts and mind, what you'd give anything for and would give anything up for, then it's not for you.
Second of all, do you have an ego strong enough to not settle for less than best in anything, yet humble enough to acknowledge you'll be in a group of incredibly talented people and will never again be the biggest fish in the pond in every, or sometimes any respect? If you're one of those guys who has never experienced not being the top dog in everything you've ever done, then Selection is going to be hard and life on the teams even harder.
Next, what's your personality style? You'll be working with a group of people on the extreme outlier end of the scale, people whose motivation, endurance, and stubborness is absolutely off the charts. We're talking A-personality to the Nth degree, a team of 12 guys who would rather cut off their nuts then be the last man in anything. And as the team leader they'll expect you to exceed them in that quality, heck even encourage them by example. If this doesn't sound like you, then don't post for selection.
Lastly, how doctrinaire are you? Do you like rules, defined roles, and keeping things simple? If so then SF is DEFINTELY not for you. If there's one thing that SF guys do better and take more seriously than mission-related stuff, it's finding creative ways to break regulations, short-cut procedures, half-ass any order they regard as being pointless or poorly decided, disregard supervisory control measures, and generally find a way to do everything their way just to drive you as the officer crazy. You'll be in charge of a team who when you give them orders, not only expects you to accomodate them in whatever method they choose to fulfill them, but will demand you assist them to do so. If you can deal with that, great.
Just so you know what I'm talking about with the last point, here's an old joke talking about the Special Forces misfit mindset vs. the Rangers (as doctrinaire as it comes), it's old but is pretty accurate:
Rangers vs Special Forces
The Chief of Staff of the Army asked his Sergeant Major, who was both Ranger and Special Forces qualified, which organization he would recommend to form a new anti-terrorist unit. The Sergeant Major responded to the General's question with this parable: If there were a hijacked Boeing 747 being held by terrorists along with its passengers and crew and an anti-terrorist unit formed either by the Rangers or the Special Forces was given a Rescue/Recovery Mission; what would you expect to happen?
Ranger Option
Forces/Equipment Committed: If the Rangers went in, they would send a Ranger company of 120 men with standard army issue equipment.
Mission Preparation: The Ranger Company First Sergeant would conduct a Hair Cut and Boots Inspection.
Infiltration Technique: They would insist on double timing, in company formation, wearing their combat equipment, and singing Jody cadence all the way to the site of the hijacked aircraft.
Actions in the Objective Area: Once they arrived, the Ranger company would establish their ORP, put out security elements, conduct a leaders recon, reapply their face cammo, and conduct final preparations for Actions on the OBJ.
Results of Operation: The Rescue/Recovery Operation would be completed within one hour; all of the terrorists and most of the passengers would have been killed, the Rangers would have sustained light casualties and the 747 would be worthless to anyone except a scrap dealer.
Special Forces Option
Forces/Equipment Committed: If Special Forces went in, they would send only a 12 man team (all SF units are divisible by 12 for some arcane historical reason) however, due to the exotic nature of their equipment the SF Team would cost the same amount to deploy as the Ranger Company.
Mission Preparation: The SF Team Sergeant would request relaxed grooming standards for the team.
Infiltration Technique: The team would insist on separate travel orders with Max Per Diem, and each would get to the site of the hijacking by his own means. At least one third of the team would insist on jumping in.
Actions in the Objective Area: Once they arrived , the SF Team would cache their military uniforms, establish a Team Room, use their illegal Team Fund to stock the unauthorized Team Room Bar, check out the situation by talking to the locals, and have a Team Meeting to discuss the merits of the terrorists' cause.
Results of Operation: The Rescue/Recovery Operation would take two weeks to complete and by that time all of the terrorists would have been killed, (and would have left signed confessions); the passengers would be ruined psychologically for the remainder of their lives; and all of the women passengers would be pregnant. The 747 would be essentially unharmed, the team would have taken no casualties but would have used up, lost, or stolen all the "high speed" equipment issued to them.