I have never used that primer, but it seems like a bonding type acrylic primer. There are several on the market and I"m sure it would work decently, but sanding is always recommended. Paint or primer will always stick best to dull and clean surfaces, not shiny ones. Sure there are deglossers you can use and there are always primers that claim they will stick to shiny surfaces well, but sanding is always a step that should not be skipped IMO. Also, the problem with acrylic primers is that if there are any stains (and when you paint over stained trim there always is) the acrylic primers will not kill them...you will always have some bleeding. I prefer BIN by Zinnser because it sticks the best and it will hold back any stains, but it is shellac based so it does stink and it is difficult to work with. You can use the acrylic primer and then spot prime the areas that bleed with a spray can of Kilz or BIN, but many times when I paint over stained trim, the stain bleed through is so widespread it's just not worth it. If you find an acrylic primer that claims it will hold back stains or says 'stain killing' on the can, this is a lie and is done just for marketing purposes. Only oil based or shellac based primers will truly kill stains.

Anyway, if you do decide to do it the right way and sand, don't be intimidated....it's really not that big of a deal. Go and buy some 3M sanding blocks, medium grit or fine grit. They also have ones with fine grit on one side and medium grit on the other. All you are interested in doing is dulling the shine...it's not like you are sanding forever trying to remove all the shine, just dull it. You want to apply some pressure, but you are not pressing so hard that this becomes some vigorous activity. An average size window with a frame around it usually takes me under 2 minutes to sand just to give you an idea. Use your available light and you can see that when you do a couple swipes with the sanding block, the sheen has dulled and is ready for primer. Also, sanding is a great way to help loosen dirt from fingerprints or whatever other contaminants have gathered there over the years so it can be dusted away before applying primer. Anything you paint over that is between the paint and the wood may ultimately affect adhesion which is why paint peels so it's very important to get rid of as much of this as you can. Good luck!

+1 on the scuff sanding and BIN recommendation. If you want to stick with SW, they have a White Pigmented Shellac based primer. Wood workers actually use shellac as a bond coat between finishes that don't play well together (something I learned while researching how to refinish my bedroom set), which is a good thing if you don't want to total sand off your trim's topcoat. Another upside to shellac and BIN is the incredibly quick cure time. I kind of like the smell, so long as there's adequate ventilation. You might want to hang flystrips, though. Bugs seem to love the smell of BIN. I had a hard time keeping the fruit or drain flies (whatever they are) away from my cabinet doors last summer.

Thanks both of you!
I don't mind roughing up the finish- I just thought I would have to sand down to raw wood in all the crevices, etc.
I will find some BIN and go with that.

I kind of like the smell, so long as there's adequate ventilation.

WOW, you're a strange one!

To the OP, ventilation is a MUST, fans, open windows, respirator, anything to get fresh air in. Bin probably smells worse than anything else out there, except maybe, original Kilz

WOW, you're a strange one!
-- What can I say, maybe I killed some braincells with it the first time around. (Actually I always had really good ventilation).

I like the smell of ammonia, too. Some people like the smell of gasoline. What can I say...brains get wired in weird ways.

Sorry if that in any way sounded like it lessened the need for ventilation! Listen to christophern: Ventilation is IMPORTANT!