Just wondering if anyone has good experience and can recommend a faster 1/4'' bit other than the birds mouth for instance? Please see the link below of what I've been using.
I read some articles on what to stay away from but not really good recommendations for what to purchase so, therefore looking for someone's good experience here.

I have been doing a lot of maple mortising for mission-style cabinetry doors and hopefully, there is a faster bit that will remain true in straight.

https://www.icscuttingtools.com/catalog/page_177A.pdf
My exact that using now: MBBDRS016X116.

Thank you!

I am using XL bottoming two flute milling bits meant for steel. They are not ideal but they were all I could source for deep mortising at the time.
I would think that the geometry for the Festool Domino bits would be ideal.
Two flute, low helix anglen split point and a 1mm radius on the corners. I am thinking of getting my sharpening service rework my bits to mimic the Festo.

Thanks for your reply Thomas! I have been doing a vast search for the right bit and I just recently came up with this one (Amana Tool 46577) but not quite sure if I'm going to make the purchase or at least not yet. Just yesterday I started looking at the Domino bit but now that you brought it up I'm going to relook at it again tomorrow when I have some time. Thanks again for your input.

That Amana bit appears to have a .1° taper. As you plunge the flutes will continue to engage all the way up the cutting depth. Maybe that will reduce chatter but it is not what you want in a mortise geometry.
I know it is heresy but have a look at metalworking end mills. There are long bits available in multiple arrangements. Stick with two flutes although I have used a four flute for mortising with success.
Price tends to be better than specialty wood bits

Thanks for the Tom. I have seen that and what I really want is a down cut bit. I'm going to have to call somebody at an endmill company and if I can get a good recommendation. I was looking at the Domion bit this morning and it looks pretty interesting. I'll let you know what I come up with. Thank you so very much Tom!!!

A down spiral is a horrible idea for deep mortising. It's going to pack the dust into the mortise and it could even build enough heat to start an ember burning. Certainly going to be some burning on the end grain of the mortise and that resists the glue.

RichC, It sounds like you have some experience in that direction so I will take your word. Do you have any suggestions of what cutter I should be looking at besides the Bi-Directional? Thanks for your input!

Rich is correct, you want to get the chips out and you will start a fire with a down spiral. Especially with a small diameter of 1/4" the ratio of diameter to depth of mortise it's going to be difficult to clear the chips without an air nozzle blowing on it.

Why are you worrying about the surface finish around a mortise? Bi-directional is not a good idea either. You will still pack sawdust into the bottom of the mortise. Just use a standard upcut. If you go to the suggested metal cutting end mills, look for ones designed to cut aluminum. They have a more aggressive spiral to get the chips out.

What equipment are you using to cut your mortises? Slot mortiser; if so what make, handheld router / manual plunge 1/8"plunge/pass, or CNC router? If CNC are you ramping in? Also what max depth do you need?
Like mentioned above down spiral bad idea; for heat & packing swarth back into cutting area.
The birdsmouth bits are great for slot mortisers and the high speed steel bits will stay pretty sharp for a good while if not pushing the plunge to hard - but still you want to make chips to take the heat and not make powdered dust i.e. heat & friction.
I do like the Festool Domino bit idea if it's deep enough? 1/4"dia 2 edge solid carbide low helix would be best; but you over 3/4"deep depth of cut is pushing rigidity issues?

The birdsmouth bit you are using has a rather long cut length for its diameter, which can lead to bit whip and irregular mortises if pushed too hard. Birdsmouth bits are easy to sharpen without any diameter change.

End mills won't cut any faster but will clear chips better, There's a far greater variety in metal cutting end mills.

It's best to keep the bit length as short as possible for the desired mortised depth and use a moderate feed rate - an oscillating mortiser like the Bacci or Pade will give the most consistent results.

If you need a deep, narrow mortise you're better off with a hollow chisel or swing chisel mortiser and integral tenons.